regulator: add support for SY8106A regulator

SY8106A is an I2C attached single output regulator made by Silergy Corp,
which is used on several Allwinner H3/H5 SBCs to control the power
supply of the ARM cores.

Add a driver for it.

Signed-off-by: Ondrej Jirman <megous@megous.com>
[Icenowy: Change commit message, remove enable/disable code, add default
 ramp_delay, add comment for go bit, add code for fixed mode voltage]
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 097f617..4efae3b 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -801,6 +801,13 @@
 	  This driver supports the internal VMMC regulator in the STw481x
 	  PMIC chips.
 
+config REGULATOR_SY8106A
+	tristate "Silergy SY8106A regulator"
+	depends on I2C && (OF || COMPILE_TEST)
+	select REGMAP_I2C
+	help
+	  This driver supports SY8106A single output regulator.
+
 config REGULATOR_TPS51632
 	tristate "TI TPS51632 Power Regulator"
 	depends on I2C