mfd: mc13xxx: Remove unnecessary spi_set_drvdata()

The driver core clears the driver data to NULL after device_release
or on probe failure. Thus, it is not needed to manually clear the
device driver data to NULL.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/mc13xxx-spi.c

@@ -149,7 +149,6 @@ static int mc13xxx_spi_probe(struct spi_device *spi)
 		ret = PTR_ERR(mc13xxx->regmap);
 		dev_err(mc13xxx->dev, "Failed to initialize register map: %d\n",
 				ret);
-		spi_set_drvdata(spi, NULL);
 		return ret;
 	}