drivers/tty/amiserial.c: add missing tty_unlock

tty_unlock is used on all other exits from the function.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/amiserial.c

@@ -1073,8 +1073,10 @@ static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
 		    (new_serial.close_delay != port->close_delay) ||
 		    (new_serial.xmit_fifo_size != state->xmit_fifo_size) ||
 		    ((new_serial.flags & ~ASYNC_USR_MASK) !=
-		     (port->flags & ~ASYNC_USR_MASK)))
+		     (port->flags & ~ASYNC_USR_MASK))) {
+			tty_unlock();
 			return -EPERM;
+		}
 		port->flags = ((port->flags & ~ASYNC_USR_MASK) |
 			       (new_serial.flags & ASYNC_USR_MASK));
 		state->custom_divisor = new_serial.custom_divisor;