[media] vivid: SDR cap add 'CU08' Complex U8 format

Add complex unsigned 8-bit sample format for SDR capture.

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>