UPSTREAM: usb: gadget: uvc: only pump video data if necessary

If the streaming endpoint is not enabled, the worker has nothing to do.
In the case buffers are still queued, this patch ensures that it will bail
out without handling any data.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20211017215017.18392-6-m.grzeschik@pengutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit f9897ec0)
Bug: 242344221
Change-Id: I1d43fb5b45f209ec98ac5ca335a04c88d536075f
Signed-off-by: Avichal Rakesh <arakesh@google.com>