serial: omap: fix potential NULL pointer dereference in serial_omap_runtime_suspend()

The dereference to 'up' should be moved below the NULL test.
Introduced by commit ddd85e225c8885b5e4419b0499ab27100e7c366a
(serial: omap: prevent runtime PM for "no_console_suspend")

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/omap-serial.c

@@ -1613,6 +1613,9 @@ static int serial_omap_runtime_suspend(struct device *dev)
 	struct uart_omap_port *up = dev_get_drvdata(dev);
 	struct omap_uart_port_info *pdata = dev->platform_data;
 
+	if (!up)
+		return -EINVAL;
+
 	/*
 	* When using 'no_console_suspend', the console UART must not be
 	* suspended. Since driver suspend is managed by runtime suspend,
@@ -1623,9 +1626,6 @@ static int serial_omap_runtime_suspend(struct device *dev)
 	    uart_console(&up->port))
 		return -EBUSY;
 
-	if (!up)
-		return -EINVAL;
-
 	if (!pdata)
 		return 0;