[SPARC64]: Fix oops on runlevel change with serial console.

Incorrect uart_write_wakeup() calls cause reference to a
NULL tty pointer in sunsab and sunzilog serial drivers.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/serial/sunsab.c

@@ -274,7 +274,6 @@ static void transmit_chars(struct uart_sunsab_port *up,
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
 		up->interrupt_mask1 |= SAB82532_IMR1_XPR;
 		writeb(up->interrupt_mask1, &up->regs->w.imr1);
-		uart_write_wakeup(&up->port);
 		return;
 	}
 

drivers/serial/sunzilog.c

@@ -517,10 +517,9 @@ static void sunzilog_transmit_chars(struct uart_sunzilog_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;