sdhci: add regulator support

This patch adds support for regulator API to sdhci core driver.
Regulators can be used to disable power in suspended state to reduce
dissipated energy.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index c98315c..ff070a3 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -249,6 +249,8 @@
 
 	const struct sdhci_ops	*ops;		/* Low level hw interface */
 
+	struct regulator	*vmmc;		/* Power regulator */
+
 	/* Internal data */
 	struct mmc_host		*mmc;		/* MMC structure */
 	u64			dma_mask;	/* custom DMA mask */