V4L/DVB (4273): Always log pvrusb2 device register / unregister events

Previously the pvrusb2 driver was conditionalizing printing of the
device register / unregister messages against a debug mask.  This sort
of information should always appear, thus this patch.

Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>