[media] exynos4-is: Move the subdev group ID definitions to public header

Move the sub-device group ID definitions to the driver's public header
so they are available to other media drivers that need to share modules
found in exynos4-is.

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>