USB: double put_tty_driver(gs_tty_driver) in gserial_setup()

If the driver cannot be registered, put_tty_driver(gs_tty_driver)
occurred here as well as at label fail.

put_tty_driver() already occurs at label fail

Signed-off-by: Roel Kluin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/u_serial.c

···
 	/* export the driver ... */
 	status = tty_register_driver(gs_tty_driver);
 	if (status) {
-		put_tty_driver(gs_tty_driver);
 		pr_err("%s: cannot register, err %d\n",
 				__func__, status);
 		goto fail;