mtd: nand: atmel_nand: 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>
Acked-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/atmel_nand.c

@@ -1659,7 +1659,6 @@ err_hw_ecc:
 err_scan_ident:
 err_no_card:
 	atmel_nand_disable(host);
-	platform_set_drvdata(pdev, NULL);
 	if (host->dma_chan)
 		dma_release_channel(host->dma_chan);
 err_ecc_ioremap: