Even if U-Boot does not use this, some libraries do. Add back this header
file so that the build does not fall back to using the host version, which
may include stdint.h and break the build due to conflicts with uint64_t,
etc.

This partially reverts commit dee37fc9

 ("Remove <inttypes.h> includes
and PRI* usages in printf() entirely")

The only change from the file that was in U-Boot until recently is that it
now comes twice as close to passing checkpatch. The remaining warnings
pertain to the typedefs, which checkpatch does not like.

Signed-off-by: Simon Glass <sjg@chromium.org>