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/Makefile b/drivers/power/pmic/Makefile
index f7bdfa5..7d6c583 100644
--- a/drivers/power/pmic/Makefile
+++ b/drivers/power/pmic/Makefile
@@ -19,6 +19,7 @@
 obj-$(CONFIG_PMIC_RN5T567) += rn5t567.o
 obj-$(CONFIG_PMIC_TPS65090) += tps65090.o
 obj-$(CONFIG_PMIC_S5M8767) += s5m8767.o
+obj-$(CONFIG_DM_PMIC_TPS65910) += pmic_tps65910_dm.o
 obj-$(CONFIG_$(SPL_)PMIC_PALMAS) += palmas.o
 obj-$(CONFIG_$(SPL_)PMIC_LP873X) += lp873x.o
 obj-$(CONFIG_$(SPL_)PMIC_LP87565) += lp87565.o