[media] V4L: Add s_rx_buffer subdev video operation

The s_rx_buffer callback allows the host to set buffer for a data being
received by the subdev, e.g. non-image frame (meta) data. This callback
can be implemented by subdevice like a MIPI CSI2 receiver, allowing the
host driver to gather additional data into frame buffer passed to user
space.

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>