[media] coda: Fix build due to iram.h rename

[media] coda: Fix build due to iram.h rename

commit c045e3f13 (ARM: imx: include iram.h rather than mach/iram.h) changed the
location of iram.h, which causes the following build error when building the coda
driver:

drivers/media/platform/coda.c:27:23: error: mach/iram.h: No such file or directory
drivers/media/platform/coda.c: In function 'coda_probe':
drivers/media/platform/coda.c:2000: error: implicit declaration of function 'iram_alloc'
drivers/media/platform/coda.c:2001: warning: assignment makes pointer from integer without a cast
drivers/media/platform/coda.c: In function 'coda_remove':
drivers/media/platform/coda.c:2024: error: implicit declaration of function 'iram_free'

Since the content of iram.h is not imx specific, move it to
include/linux/platform_data/imx-iram.h instead. This is an intermediate solution
until the i.MX iram allocator is converted to the generic SRAM allocator.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>