usb: gadget: legacy: fix error return code in gfs_bind

We must return negative error code -ENOMEM if function
'usb_otg_descriptor_alloc()' fails.
Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Link: https://lore.kernel.org/r/20230621124323.47183-1-harperchen1110@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/legacy/g_ffs.c

@@ -389,8 +389,10 @@ static int gfs_bind(struct usb_composite_dev *cdev)
 		struct usb_descriptor_header *usb_desc;
 
 		usb_desc = usb_otg_descriptor_alloc(cdev->gadget);
-		if (!usb_desc)
+		if (!usb_desc) {
+			ret = -ENOMEM;
 			goto error_rndis;
+		}
 		usb_otg_descriptor_init(cdev->gadget, usb_desc);
 		gfs_otg_desc[0] = usb_desc;
 		gfs_otg_desc[1] = NULL;