Define a v4l2_device instance in the pvrusb2 driver and initialize /
tear it down appropriately.  This is a step in the v4l2-subdev
adoption effort.
Signed-off-by: NMike Isely <isely@pobox.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>