[media] uvc: Depend on VIDEO_V4L2

The uvcvideo driver lost its dependency on VIDEO_V4L2 during the big
media directory reorganization. Add it back.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/uvc/Kconfig

 config USB_VIDEO_CLASS
 	tristate "USB Video Class (UVC)"
+	depends on VIDEO_V4L2
 	select VIDEOBUF2_VMALLOC
 	---help---
 	  Support for the USB Video Class (UVC).  Currently only video