spi: 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: Mark Brown <broonie@linaro.org>
diff --git a/drivers/spi/spi-ti-ssp.c b/drivers/spi/spi-ti-ssp.c
index 10606fc..7d20e12 100644
--- a/drivers/spi/spi-ti-ssp.c
+++ b/drivers/spi/spi-ti-ssp.c
@@ -283,7 +283,7 @@
 	struct device *dev = &pdev->dev;
 	int error = 0;
 
-	pdata = dev->platform_data;
+	pdata = dev_get_platdata(dev);
 	if (!pdata) {
 		dev_err(dev, "platform data not found\n");
 		return -EINVAL;