[media] s5p-jpeg: Perform fourcc downgrade only for Exynos4x12 SoCs

[media] s5p-jpeg: Perform fourcc downgrade only for Exynos4x12 SoCs

Change the driver variant check from "is not S5PC210"
to "is Exynos4" while checking whether YUV format needs
to be downgraded in order to prevent upsampling which
is not supported by Exynos4 SoCs family.

Change-Id: Iedda710f6e6ea62555e2bde9481f7e789eb36fb9
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>