mmc: cb710: use to_platform_device()

Use to_platform_device() instead of open-coding it.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/cb710-mmc.h

@@ -29,8 +29,7 @@ static inline struct mmc_host *cb710_slot_to_mmc(struct cb710_slot *slot)
 
 static inline struct cb710_slot *cb710_mmc_to_slot(struct mmc_host *mmc)
 {
-	struct platform_device *pdev = container_of(mmc_dev(mmc),
-		struct platform_device, dev);
+	struct platform_device *pdev = to_platform_device(mmc_dev(mmc));
 	return cb710_pdev_to_slot(pdev);
 }