usb: gadget: composite: Fix return value in case of error

In 'composite_os_desc_req_prepare', if one of the memory allocations fail,
0 will be returned, which means success.
We should return -ENOMEM instead.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/composite.c

@@ -2126,14 +2126,14 @@ int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
 
 	cdev->os_desc_req = usb_ep_alloc_request(ep0, GFP_KERNEL);
 	if (!cdev->os_desc_req) {
-		ret = PTR_ERR(cdev->os_desc_req);
+		ret = -ENOMEM;
 		goto end;
 	}
 
 	/* OS feature descriptor length <= 4kB */
 	cdev->os_desc_req->buf = kmalloc(4096, GFP_KERNEL);
 	if (!cdev->os_desc_req->buf) {
-		ret = PTR_ERR(cdev->os_desc_req->buf);
+		ret = -ENOMEM;
 		kfree(cdev->os_desc_req);
 		goto end;
 	}