Staging: emxx_udc: Return NULL instead of 0.

Return NULL instead of 0 from nbu2ss_ep_alloc_request(),if req pointer is NULL.
Signed-off-by: NSandhya Bankar <bankarsandhya512@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/emxx_udc/emxx_udc.c

@@ -2625,7 +2625,7 @@ static struct usb_request *nbu2ss_ep_alloc_request(
 
 	req = kzalloc(sizeof(*req), gfp_flags);
 	if (!req)
-		return 0;
+		return NULL;
 
 #ifdef USE_DMA
 	req->req.dma = DMA_ADDR_INVALID;