[media] v4l: add stream format for SDR receiver

Add new V4L2 stream format definition, V4L2_BUF_TYPE_SDR_CAPTURE,
for SDR receiver.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>