[media] use v4l2_mc_usb_media_device_init() on most USB devices

Except for the usbuvc driver (with has an embedded media_device
struct on it), the other drivers have a pointer to media_device.

On those drivers, replace their own implementation for the core
one. That warrants that those subdev drivers will fill the
media_device info the same way.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>