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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/legacy/g_ffs.c

···
 		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;