usb: dwc3: omap: signedness bug in dwc3_omap_set_utmi_mode()

"ret" should be signed.  It's only used for zero and negative error
codes.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/dwc3-omap.c

@@ -425,7 +425,7 @@ static void dwc3_omap_set_utmi_mode(struct dwc3_omap *omap)
 
 static int dwc3_omap_extcon_register(struct dwc3_omap *omap)
 {
-	u32			ret;
+	int			ret;
 	struct device_node	*node = omap->dev->of_node;
 	struct extcon_dev	*edev;