wireless: libertas: 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: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/if_spi.c

@@ -93,7 +93,6 @@ static void free_if_spi_card(struct if_spi_card *card)
 		list_del(&packet->list);
 		kfree(packet);
 	}
-	spi_set_drvdata(card->spi, NULL);
 	kfree(card);
 }