[media] pwc: Use v4l2-device and v4l2-fh

This is a preperation patch for adding support for control events. Actually
enabling support for control events will be done in a separate patch, as that
depends on the necessary poll changes going upstream

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