usb: dwc2/gadget: break infinite loop in endpoint disable code

This patch fixes possible freeze caused by infinite loop in interrupt
context.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Cc: stable <stable@vger.kernel.org> # 3.16
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc2/gadget.c

@@ -1649,6 +1649,7 @@ static void s3c_hsotg_txfifo_flush(struct s3c_hsotg *hsotg, unsigned int idx)
 			dev_err(hsotg->dev,
 				"%s: timeout flushing fifo (GRSTCTL=%08x)\n",
 				__func__, val);
+			break;
 		}
 
 		udelay(1);