[media] s5p-fimc: Use vb2 ioctl helpers in fimc-lite

Replace some ioctl, file and video buffer queue operation handlers
with the videobuf2 helpers. This allows to get rid of significant
amount of boilerplate.

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>