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

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);

---
 drivers/usb/gadget/udc/amd5536udc_pci.c | 3 +++
 1 file changed, 3 insertions(+)

index c80f9bd51b75..a36913ae31f9 100644
@@ -170,6 +170,9 @@ static int udc_pci_probe(
 		retval = -ENODEV;
 		goto err_probe;
 	}
+
+	udc = dev;
+
 	return 0;
 
 err_probe:

2.34.1