regulator: AXP20x: Add support for regulators subsystem

AXP202 and AXP209 come with two synchronous step-down DC-DCs and five
LDOs. This patch introduces basic support for those regulators.

Signed-off-by: Carlo Caione <carlo@caione.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 903eb37..65e5d7d 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -139,6 +139,13 @@
 	  AS3722 PMIC. This will enable support for all the software
 	  controllable DCDC/LDO regulators.
 
+config REGULATOR_AXP20X
+	tristate "X-POWERS AXP20X PMIC Regulators"
+	depends on MFD_AXP20X
+	help
+	  This driver provides support for the voltage regulators on the
+	  AXP20X PMIC.
+
 config REGULATOR_BCM590XX
 	tristate "Broadcom BCM590xx PMU Regulators"
 	depends on MFD_BCM590XX