mfd: Add an AS3711 PMIC MFD driver

AS3711 is a PMIC with multiple DCDC and LDO power supplies, GPIOs, an RTC,
a battery charger and a general purpose ADC. This patch adds support for
the MFD with support for a regulator driver and a backlight driver.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index f5b839b..475c266 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1103,6 +1103,15 @@
 	  Retu is a multi-function device found on Nokia Internet Tablets
 	  (770, N800 and N810).
 
+config MFD_AS3711
+	bool "Support for AS3711"
+	select MFD_CORE
+	select REGMAP_I2C
+	select REGMAP_IRQ
+	depends on I2C=y
+	help
+	  Support for the AS3711 PMIC from AMS
+
 endmenu
 endif