[media] v4l2: add support for SDR transmitter

New IOCTL ops:
vidioc_enum_fmt_sdr_out
vidioc_g_fmt_sdr_out
vidioc_s_fmt_sdr_out
vidioc_try_fmt_sdr_out

New vb2 buffertype:
V4L2_BUF_TYPE_SDR_OUTPUT

New v4l2 capability:
V4L2_CAP_SDR_OUTPUT

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