i2c: use dev_get_drvdata() to get private data in suspend/resume hooks

Several drivers call to_platform_device() to get platform_device
and pass it to platform_get_drvdata().  In platform_get_drvdata(),
the platform_device is converted back to struct device again.

Use dev_get_drvdata() to avoid platform_device/device dance.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> (for DesignWare only)
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-st.c

@@ -745,8 +745,7 @@ static int st_i2c_xfer(struct i2c_adapter *i2c_adap,
 #ifdef CONFIG_PM_SLEEP
 static int st_i2c_suspend(struct device *dev)
 {
-	struct platform_device *pdev = to_platform_device(dev);
-	struct st_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
+	struct st_i2c_dev *i2c_dev = dev_get_drvdata(dev);
 
 	if (i2c_dev->busy)
 		return -EBUSY;