staging: regulator: hi6421v600-regulator: add it to the building system

Change the binding logic to ensure that the PMIC SPMI
driver will run before the regulator code and add it to the
building system.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2992dc49945dcfb07c4bd96fa5c288c4e679701a.1597647359.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/hikey9xx/Kconfig

@@ -15,7 +15,6 @@ config MFD_HI6421_SPMI
 	tristate "HiSilicon Hi6421v600 SPMI PMU/Codec IC"
 	depends on OF
 	select MFD_CORE
-	select REGMAP_MMIO
 	help
 	  Add support for HiSilicon Hi6421v600 SPMI PMIC. Hi6421 includes
 	  multi-functions, such as regulators, RTC, codec, Coulomb counter,
@@ -25,3 +24,12 @@ config MFD_HI6421_SPMI
 	  individual components like voltage regulators under corresponding
 	  menus in order to enable them.
 	  We communicate with the Hi6421v600 via a SPMI bus.
+
+# to be placed at drivers/regulator
+config REGULATOR_HI6421V600
+	tristate "HiSilicon Hi6421v600 PMIC voltage regulator support"
+	depends on MFD_HI6421_PMIC && OF
+	help
+	  This driver provides support for the voltage regulators on
+	  HiSilicon Hi6421v600 PMU / Codec IC.
+	  This is used on Kirin 3670 boards, like HiKey 970.

drivers/staging/hikey9xx/Makefile

 # SPDX-License-Identifier: GPL-2.0
 
-obj-$(CONFIG_SPMI_HISI3670)	+= hisi-spmi-controller.o
-obj-$(CONFIG_MFD_HI6421_SPMI)	+= hi6421-spmi-pmic.o
+obj-$(CONFIG_SPMI_HISI3670)		+= hisi-spmi-controller.o
+obj-$(CONFIG_MFD_HI6421_SPMI)		+= hi6421-spmi-pmic.o
+obj-$(CONFIG_REGULATOR_HI6421V600)	+= hi6421v600-regulator.o