V4L/DVB (6293): V4L: convert struct class_device to struct device

The currently used "struct class_device" will be removed from the
kernel. Here is a patch that converts all users in drivers/media/video/
to struct device.

Reviewed-by: Thierry Merle <thierry.merle@free.fr>
Reviewed-by: Mike Isely <isely@pobox.com>
Reviewed-by: Luca Risolia <luca.risolia@studio.unibo.it>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>