[media] v4l: mem2mem: port to videobuf2

Port memory-to-memory framework to videobuf2 framework.

Add support for multi-planar Video for Linux 2 API extensions to the
memory-to-memory driver framework.

Based on the original patch written by Pawel Osciak.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>