usb: dwc2: gadget: don't block after fifo flush timeout

Can't stay in the loop forever. Break it after timeout.
Tested-by: NRobert Baldyga <r.baldyga@samsung.com>
Acked-by: NPaul Zimmerman <paulz@synopsys.com>
Signed-off-by: NGregory Herrero <gregory.herrero@intel.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/dwc2/gadget.c

@@ -230,6 +230,7 @@ static void s3c_hsotg_init_fifo(struct dwc2_hsotg *hsotg)
 			dev_err(hsotg->dev,
 				"%s: timeout flushing fifos (GRSTCTL=%08x)\n",
 				__func__, val);
+			break;
 		}
 
 		udelay(1);