regulator: add STw481x VMMC driver

The ST Microelectronics STw481x PMIC used for the Nomadik
has one single software-controlled regulator for VMMC.
This driver registers directly to the compatible string
as there is just one regulator.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index dfe5809..d957010 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -429,6 +429,14 @@
 	  on TI SoCs may be unstable without enabling this as it provides
 	  device specific optimized bias to allow/optimize functionality.
 
+config REGULATOR_STW481X_VMMC
+	bool "ST Microelectronics STW481X VMMC regulator"
+	depends on MFD_STW481X
+	default y if MFD_STW481X
+	help
+	  This driver supports the internal VMMC regulator in the STw481x
+	  PMIC chips.
+
 config REGULATOR_TPS51632
 	tristate "TI TPS51632 Power Regulator"
 	depends on I2C