usb: gadget: uvc: separately compile some components of f_uvc

Compile uvc_queue, uvc_v4l2, uvc_video separately so that later they can
be all combined in a separately compiled f_uvc.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Tested-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
[Make uvc_v4l2_ioctl_ops non-static]
[Rename __UVC__V4L2__H__ and __UVC__VIDEO__H__]
[Update MAINTAINERS]
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>