media: coda: add JPEG downscale support

The JPEG decoder in the CODA960 VPU can downscale images while decoding,
with a factor of 1/2, 1/4, or 1/8.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>