Fixes below compilation warning when musb driver is compiled for
PIO mode:
drivers/usb/musb/musb_gadget.c: In function 'musb_g_rx':
drivers/usb/musb/musb_gadget.c:840:
		warning: label 'exit' defined but not used
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
                if (!request)
                        return;
        }
+#if defined(CONFIG_USB_INVENTRA_DMA) || defined(CONFIG_USB_TUSB_OMAP_DMA)
 exit:
+#endif
        /* Analyze request */
        rxstate(musb, to_musb_request(request));
 }