usb: dwc3: omap: use the macro we already have

trivial patch, no functional changes.
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/dwc3/dwc3-omap.c

@@ -311,7 +311,8 @@ static int __devinit dwc3_omap_probe(struct platform_device *pdev)
 	}
 
 	/* enable all IRQs */
-	dwc3_writel(omap->base, USBOTGSS_IRQENABLE_SET_0, 0x01);
+	reg = USBOTGSS_IRQO_COREIRQ_ST;
+	dwc3_writel(omap->base, USBOTGSS_IRQENABLE_SET_0, reg);
 
 	reg = (USBOTGSS_IRQ1_OEVT |
 			USBOTGSS_IRQ1_DRVVBUS_RISE |