usb: gadget: fsl_qe_udc: signedness bug in qe_get_frame()

We can't assign -EINVAL to a u16.

Fixes: 3948f0e ('usb: add Freescale QE/CPM USB peripheral controller driver')
Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/fsl_qe_udc.c

@@ -1878,11 +1878,8 @@ static int qe_get_frame(struct usb_gadget *gadget)
 
 	tmp = in_be16(&udc->usb_param->frame_n);
 	if (tmp & 0x8000)
-		tmp = tmp & 0x07ff;
-	else
-		tmp = -EINVAL;
-
-	return (int)tmp;
+		return tmp & 0x07ff;
+	return -EINVAL;
 }
 
 static int fsl_qe_start(struct usb_gadget *gadget,