[media] s5p-fimc: Use vb2 ioctl/fop helpers in FIMC capture driver

mmap/poll file operation and several ioctl handlers are replaced
with the vb2 helper functions. Some helpers are used indirectly
to maintain the buffer queue ownership.

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>