V4L/DVB (11380): v4l2-subdev: change s_routing prototype

It is no longer needed to use a struct pointer as argument, since v4l2_subdev
doesn't require that ioctl-like approach anymore. Instead just pass the input,
output and config (new!) arguments directly.

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