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/max3100.c b/drivers/tty/serial/max3100.c
index 35866d5..79f9a9e 100644
--- a/drivers/tty/serial/max3100.c
+++ b/drivers/tty/serial/max3100.c
@@ -779,7 +779,7 @@
 	max3100s[i]->irq = spi->irq;
 	spin_lock_init(&max3100s[i]->conf_lock);
 	spi_set_drvdata(spi, max3100s[i]);
-	pdata = spi->dev.platform_data;
+	pdata = dev_get_platdata(&spi->dev);
 	max3100s[i]->crystal = pdata->crystal;
 	max3100s[i]->loopback = pdata->loopback;
 	max3100s[i]->poll_time = pdata->poll_time * HZ / 1000;