[media] s5p-fimc: Enable FIMC-LITE driver only for SOC_EXYNOS4x12

Allow to compile-in the FIMC-LITE driver only on Exynos4212,
Exynos4412 and Exynos5250 SoC where the device is available.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>