V4L/DVB (5417): First unregister the driver, and then free the memory.

ivtv_remove which is called by pci_unregister_driver was still using
memory that was already freed. Ouch.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>