mtd: maps: rbtx4939-flash: remove unnecessary platform_set_drvdata()

The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d0631001288a5974afc0b2a5f568bcdecb4d
(device-core: Ensure drvdata = NULL when no driver is bound).
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: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/maps/rbtx4939-flash.c

@@ -34,7 +34,6 @@ static int rbtx4939_flash_remove(struct platform_device *dev)
 	info = platform_get_drvdata(dev);
 	if (!info)
 		return 0;
-	platform_set_drvdata(dev, NULL);
 
 	if (info->mtd) {
 		struct rbtx4939_flash_data *pdata = dev->dev.platform_data;