mmc: remove unnecessary platform_set_drvdata()

The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d06310
(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>
Acked-by: Sonic Zhang <sonic.zhang@analog.com>
Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Tony Prisk <linux@prisktech.co.nz>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/wmt-sdmmc.c

@@ -927,8 +927,6 @@ static int wmt_mci_remove(struct platform_device *pdev)
 
 	mmc_free_host(mmc);
 
-	platform_set_drvdata(pdev, NULL);
-
 	dev_info(&pdev->dev, "WMT MCI device removed\n");
 
 	return 0;