Fixed unregistering the vbi device for cards without analog tuner.
Thanks to Marco Schluessler <marco@lordzodiac.de> for pointing out this bug.
Signed-off-by: NOliver Endriss <o.endriss@gmx.de>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>