UPSTREAM: usb: gadget: uvc: ensure the vdev is unset

Since the uvc video device is created on demand, we have to ensure
that the struct is always zeroed. Otherwise the previous settings
might collide with the new values.

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/20211017215017.18392-7-m.grzeschik@pengutronix.de


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

(cherry picked from commit e4ce9ed8)
Bug: 242344221
Change-Id: Iff680809310e34b0341a902250f208be4e6cdb6e
Signed-off-by: Avichal Rakesh <arakesh@google.com>
(cherry picked from commit c5907842)