usb: gadget: udc: fix NULL dereference in remove()

[ Upstream commit 016da9c6

 ]

The "udc" pointer was never set in the probe() function so it will
lead to a NULL dereference in udc_pci_remove() when we do:

	usb_del_gadget_udc(&udc->gadget);

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/ZG+A/dNpFWAlCChk@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>