V4L/DVB (3712): Fix video input setting of em28xx, use _INT_S_VIDEO_ROUTING in tvp5150

- Use new routing input defines in em28xx-cards.c
- Fix S-Video settings for tvp5150-based cards (input was copied from saa7115
  based cards and worked only because S-Video was selected in the default: case)
- Replace VIDIOC_S_INPUT by VIDIOC_INT_S_VIDEO_ROUTING in em28xx-video.c
- Remove the now obsolete VIDIOC_S_INPUT handler in saa7115.c
- Add VIDIOC_INT_G/S_VIDEO_ROUTING in tvp5150.c
- Add new media/tvp5150.h with the routing defines.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>