fdt: Fix alignment issue when reading 64-bits properties from fdt

The FDT specification [0] gives a requirement of aligning properties on
32-bits. Make sure that the compiler is aware of this constraint when
accessing 64-bits properties.

[0]: https://github.com/devicetree-org/devicetree-specification/blob/master/source/flattened-format.rst

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
31 jobs for testing in 136 minutes and 40 seconds (queued for 10 seconds)
Status Job ID Name Coverage
  Testsuites
passed #24644
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Build envtools

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Build tools-only

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passed #24642
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Check for configs without MAINTAINERS entry

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passed #24645
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Run binman, buildman, dtoc and patman testsuites

00:01:03

passed #24639
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cppcheck

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passed #24640
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grep TODO/FIXME/HACK

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passed #24641
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sloccount

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  Test.Py
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evb-ast2500 test.py

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passed #24652
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integratorcp_cm926ejs test.py

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passed #24659
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qemu-ppce500 test.py

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passed #24660
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qemu-riscv64 test.py

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passed #24661
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qemu-x86 test.py

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passed #24662
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qemu-x86_64 test.py

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passed #24653
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qemu_arm test.py

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passed #24654
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qemu_arm64 test.py

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passed #24655
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qemu_mips test.py

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passed #24657
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qemu_mips64 test.py

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passed #24658
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qemu_mips64el test.py

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passed #24656
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qemu_mipsel test.py

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passed #24646
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sandbox test.py

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passed #24649
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sandbox_flattree test.py

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passed #24647
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sandbox_spl test.py

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passed #24650
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vexpress_ca15_tc2 test.py

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passed #24651
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vexpress_ca9x4 test.py

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passed #24664
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xilinx_versal_virt test.py

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passed #24665
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xtfpga test.py

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passed #24663
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zynq_zc702 test.py

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  World Build
passed #24666
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build all 32bit ARM platforms

00:50:56

passed #24667
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build all 64bit ARM platforms

00:19:33

passed #24668
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build all PowerPC platforms

00:19:52

passed #24669
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build all other platforms

00:09:51