[media] em28xx: move vinmode and vinctrl data from struct em28xx to struct v4l2

The video input mode and control data also belong only to the
analog side. move them to struct em28xx_v4l.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>