usb: gadget: composite: Fix function used to free memory

'cdev->os_desc_req' has been allocated with 'usb_ep_alloc_request()' so
'usb_ep_free_request()' should be used to free it.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/composite.c

@@ -2147,7 +2147,7 @@ int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
 	cdev->os_desc_req->buf = kmalloc(4096, GFP_KERNEL);
 	if (!cdev->os_desc_req->buf) {
 		ret = -ENOMEM;
-		kfree(cdev->os_desc_req);
+		usb_ep_free_request(ep0, cdev->os_desc_req);
 		goto end;
 	}
 	cdev->os_desc_req->context = cdev;