power: pmic/regulator: Add basic support for TPS65910

Texas Instrument's TPS65910 PMIC contains 3 buck DC-DC converts, one
boost DC-DC converter and 8 LDOs. This patch implements driver model
support for the TPS65910 PMIC and its regulators making the get/set
API for regulator value/enable available.
This patch depends on the patch "am33xx: Add a function to query MPU
voltage in uV" to build correctly. For boards relying on the DT
include file tps65910.dtsi the v3 patch "power: extend prefix match
to regulator-name property" and an appropriate regulator naming is
also required.

Signed-off-by: Felix Brack <fb@ltec.ch>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/power/pmic/Kconfig b/drivers/power/pmic/Kconfig
index e3f9e4d..5d49c93 100644
--- a/drivers/power/pmic/Kconfig
+++ b/drivers/power/pmic/Kconfig
@@ -201,3 +201,11 @@
 	The MC34VR500 is used in conjunction with the FSL T1 and LS1 series
 	SoC. It provides 4 buck DC-DC convertors and 5 LDOs, and it is accessed
 	via an I2C interface.
+
+config DM_PMIC_TPS65910
+	bool "Enable driver for Texas Instruments TPS65910 PMIC"
+	depends on DM_PMIC
+	---help---
+	The TPS65910 is a PMIC containing 3 buck DC-DC converters, one boost
+	DC-DC converter, 8 LDOs and a RTC. This driver binds the SMPS and LDO
+	pmic children.