[media] v4l: soc-camera: Remove videobuf1 support

All remaining soc-camera drivers use videobuf2, drop support for
videobuf1.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: also drop 'select VIDEOBUF_GEN' from Kconfig]

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>