regulator: new drivers for AD5398 and AD5821

The AD5398 and AD5821 are single 10-bit DAC with 120 mA output current
sink capability. They feature an internal reference and operates from
a single 2.7 V to 5.5 V supply.

This driver supports both the AD5398 and the AD5821.  It adapts into the
voltage and current framework.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 04f2e08..679ea37 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -201,5 +201,11 @@
 	help
 	  This driver supports 88PM8607 voltage regulator chips.
 
+config REGULATOR_AD5398
+	tristate "Analog Devices AD5398/AD5821 regulators"
+	depends on I2C
+	help
+	  This driver supports AD5398 and AD5821 current regulator chips.
+	  If building into module, its name is ad5398.ko.
 endif