V4L/DVB (7376): Improve compile-time type-checking in videobuf

Make the dev member of the struct videobuf_queue of type "struct device *"
to avoid future problems. Also change the prototype of the
videobuf_queue_core_init() function.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>