mfd: Add bcm590xx pmu driver

Add a driver for the BCM590xx PMU multi-function devices. The driver
initially supports regmap initialization and instantiation of the
voltage regulator device function of the PMU.

Signed-off-by: Matt Porter <mporter@linaro.org>
Reviewed-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index d22ca0f..7587c9e 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -59,6 +59,14 @@
 	  additional drivers must be enabled in order to use the
 	  functionality of the device.
 
+config MFD_BCM590XX
+	tristate "Broadcom BCM590xx PMUs"
+	select MFD_CORE
+	select REGMAP_I2C
+	depends on I2C
+	help
+	  Support for the BCM590xx PMUs from Broadcom
+
 config MFD_CROS_EC
 	tristate "ChromeOS Embedded Controller"
 	select MFD_CORE