usb: gadget: mv_u3d: add check for dma mapping error

mv_u3d_req_to_trb() does not check for dma mapping errors.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/mv_u3d_core.c

@@ -462,6 +462,12 @@ static int mv_u3d_req_to_trb(struct mv_u3d_req *req)
 					req->trb_head->trb_hw,
 					trb_num * sizeof(*trb_hw),
 					DMA_BIDIRECTIONAL);
+		if (dma_mapping_error(u3d->gadget.dev.parent,
+					req->trb_head->trb_dma)) {
+			kfree(req->trb_head->trb_hw);
+			kfree(req->trb_head);
+			return -EFAULT;
+		}
 
 		req->chain = 1;
 	}