[media] v4l: define own IOCTL ops for SDR FMT

Use own format ops for SDR data:
vidioc_enum_fmt_sdr_cap
vidioc_g_fmt_sdr_cap
vidioc_s_fmt_sdr_cap
vidioc_try_fmt_sdr_cap

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>