mfd: Add STw481x driver

This adds a driver for the STw481x PMICs found in the Nomadik
family of platforms. This one uses pure device tree probing.
Print some of the OTP registers on boot and register a regulator
MFD child.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 914c3d1..d078fe4a 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1151,6 +1151,16 @@
 	  core support for the WM8994, in order to use the actual
 	  functionaltiy of the device other drivers must be enabled.
 
+config MFD_STW481X
+	bool "Support for ST Microelectronics STw481x"
+	depends on I2C && ARCH_NOMADIK
+	select REGMAP_I2C
+	select MFD_CORE
+	help
+	  Select this option to enable the STw481x chip driver used
+	  in various ST Microelectronics and ST-Ericsson embedded
+	  Nomadik series.
+
 endmenu
 endif