media: uvcvideo: Undup use uvc_endpoint_max_bpi() code

Replace manual decoding of psize in uvc_parse_streaming(), with the code
from uvc_endpoint_max_bpi(). It also handles usb3 devices.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>