[media] staging-usbvideo: remove

With the new gspca v4l2 vicam driver, there is no more reason to keep the
old v4l1 usbvideo vicam driver around, and since that is the last
usbvideo framework using driver, the old usbvideo framework itself can
go too.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>