serial: use dev_get_platdata()

Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/arc_uart.c b/drivers/tty/serial/arc_uart.c
index cbf1d15..2f195f0 100644
--- a/drivers/tty/serial/arc_uart.c
+++ b/drivers/tty/serial/arc_uart.c
@@ -528,7 +528,7 @@
 	unsigned long *plat_data;
 	struct arc_uart_port *uart = &arc_uart_ports[dev_id];
 
-	plat_data = ((unsigned long *)(pdev->dev.platform_data));
+	plat_data = (unsigned long *)dev_get_platdata(&pdev->dev);
 	if (!plat_data)
 		return -ENODEV;