usb: gadget: u_serial: fix switch off blocked

When a device is switched off by software, gserial_cleanup will
be called, and switch off will be blocked in this function
because wake_up_interruptible() in gs_close() can not wake_up
the wait_event() in gserial_cleanup(), it should be changed to
wake_up() to match the wait_event().
Signed-off-by: Haipeng YU <haipeng.yu@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/u_serial.c

@@ -887,7 +887,7 @@ static void gs_close(struct tty_struct *tty, struct file *file)
 	pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
 			port->port_num, tty, file);
 
-	wake_up_interruptible(&port->port.close_wait);
+	wake_up(&port->port.close_wait);
 exit:
 	spin_unlock_irq(&port->port_lock);
 }