[media] coda: add support for native order firmware files with Freescale header

Freescale distribute their VPU firmware files with a 16 byte header
in BIT processor native order. This patch allows to detect the header
and to reorder the firmware on the fly.
With this patch it should be possible to use the distributed
vpu_fw_imx{53,6q,6d}.bin files directly after renaming them to
v4l-coda*-imx{53,6q,6dl}.bin.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>