dma_unmap_sg() is being called twice after completing the
task. Looks like this is a copy paste error when creating
des driver.
With this the following warn appears during boot:

[    4.210457] ------------[ cut here ]------------
[    4.215114] WARNING: CPU: 0 PID: 0 at lib/dma-debug.c:1080 check_unmap+0x710/0x9a0()
[    4.222899] omap-des 480a5000.des: DMA-API: device driver tries to free DMA memory it has not allocated [device address=0x00000000ab2ce000] [size=8 bytes]
[    4.236785] Modules linked in:
[    4.239860] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.14.39-02999-g1bc045a-dirty #182
[    4.247918] [<c001678c>] (unwind_backtrace) from [<c0012574>] (show_stack+0x10/0x14)
[    4.255710] [<c0012574>] (show_stack) from [<c05a37e8>] (dump_stack+0x84/0xb8)
[    4.262977] [<c05a37e8>] (dump_stack) from [<c0046464>] (warn_slowpath_common+0x68/0x8c)
[    4.271107] [<c0046464>] (warn_slowpath_common) from [<c004651c>] (warn_slowpath_fmt+0x30/0x40)
[    4.279854] [<c004651c>] (warn_slowpath_fmt) from [<c02d50a4>] (check_unmap+0x710/0x9a0)
[    4.287991] [<c02d50a4>] (check_unmap) from [<c02d5478>] (debug_dma_unmap_sg+0x90/0x19c)
[    4.296128] [<c02d5478>] (debug_dma_unmap_sg) from [<c04a77d8>] (omap_des_done_task+0x1cc/0x3e4)
[    4.304963] [<c04a77d8>] (omap_des_done_task) from [<c004a090>] (tasklet_action+0x84/0x124)
[    4.313370] [<c004a090>] (tasklet_action) from [<c004a4ac>] (__do_softirq+0xf0/0x20c)
[    4.321235] [<c004a4ac>] (__do_softirq) from [<c004a840>] (irq_exit+0x98/0xec)
[    4.328500] [<c004a840>] (irq_exit) from [<c000f9ac>] (handle_IRQ+0x50/0xb0)
[    4.335589] [<c000f9ac>] (handle_IRQ) from [<c0008688>] (gic_handle_irq+0x28/0x5c)

Removing the duplicate call to dma_unmap_sg().

Cc: stable@vger.kernel.org
Reported-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>