[media] s5p-jpeg: Ensure correct capture format for Exynos4x12

Adjust capture format to the Exynos4x12 device limitations,
according to the subsampling value parsed from the source
JPEG image header. If the capture format was set to YUV with
subsampling lower than the one of the source JPEG image
the decoding process would not succeed.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>