V4L/DVB (7562): videobuf: Require spinlocks for all videobuf users

A spinlock is necessary for queue_cancel to work with every driver in the tree.
Otherwise a race exists between IRQ handlers removing buffers from the queue
and queue_cancel invalidating the queue.

Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>