usb: gadget: uvc: dont drop frames if zero length packages are late

If the request that was missed was zero bytes long, it
is likely that the overall transferred frame was not affected.
So don't flag the frame incomplete in that case.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20240214-uvc-error-tag-v1-1-37659a3877fe@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>