mfd: sec-core: Prepare regulators for suspend state to reduce power-consumption

This patch use regulator_suspend_prepare() function to prepare the proper state
of regulators for suspend state to remove un-necessary leakage power-consumption.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index defe58d..b8d9ca0 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -587,6 +587,7 @@
 	select MFD_CORE
 	select REGMAP_I2C
 	select REGMAP_IRQ
+	select REGULATOR
 	help
 	 Support for the Samsung Electronics MFD series.
 	 This driver provides common support for accessing the device,