usb: gadget: legacy: fix error return code of multi_bind()

When usb_otg_descriptor_alloc() returns NULL to usb_desc, no error
return code of multi_bind() is assigned.
To fix this bug, status is assigned with -ENOMEM in this case.
Reported-by: NTOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Link: https://lore.kernel.org/r/20210307084545.21775-1-baijiaju1990@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/legacy/multi.c

@@ -399,8 +399,10 @@ static int __ref multi_bind(struct usb_composite_dev *cdev)
 		struct usb_descriptor_header *usb_desc;
 
 		usb_desc = usb_otg_descriptor_alloc(gadget);
-		if (!usb_desc)
+		if (!usb_desc) {
+			status = -ENOMEM;
 			goto fail_string_ids;
+		}
 		usb_otg_descriptor_init(gadget, usb_desc);
 		otg_desc[0] = usb_desc;
 		otg_desc[1] = NULL;