[SERIAL] ip22zilog: Fix oops on runlevel change with serial console

Incorrect uart_write_wakeup() calls cause reference to a NULL tty
pointer.  This has been fixed in the sunsab and sunzilog serial drivers
in October 2005.  Update the ip22zilog, which is based on sunzilog,
accordingly.
Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk

drivers/serial/ip22zilog.c

@@ -420,10 +420,8 @@ static void ip22zilog_transmit_chars(struct uart_ip22zilog_port *up,
 	if (up->port.info == NULL)
 		goto ack_tx_int;
 	xmit = &up->port.info->xmit;
-	if (uart_circ_empty(xmit)) {
-		uart_write_wakeup(&up->port);
+	if (uart_circ_empty(xmit))
 		goto ack_tx_int;
-	}
 	if (uart_tx_stopped(&up->port))
 		goto ack_tx_int;