fotg210-udc: Add missing completion handler

fotg210-udc: Add missing completion handler

[ Upstream commit e55f67391fa986f7357edba0ca59e668d99c3a5f ]

This is used when responding to GET_STATUS requests. Without this, it
crashes on completion.

Fixes: b84a8dee23fd ("usb: gadget: add Faraday fotg210_udc driver")
Signed-off-by: Fabian Vogt <fabian@ritter-vogt.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230123073508.2350402-2-linus.walleij@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>