dm: Add support for simple-pm-bus

This type of bus is used in Linux to designate buses which have power
domains and/or clocks which need to be enabled before their child devices
can be used. Because power domains are automatically enabled before probing
in U-Boot, we just need to enable any clocks present.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig
index a3b0399..a594899 100644
--- a/drivers/core/Kconfig
+++ b/drivers/core/Kconfig
@@ -195,6 +195,13 @@
 	  Supports the 'simple-bus' driver, which is used on some systems
 	  in SPL.
 
+config SIMPLE_PM_BUS
+	bool "Support simple-pm-bus driver"
+	depends on DM && OF_CONTROL && CLK && POWER_DOMAIN
+	help
+	  Supports the 'simple-pm-bus' driver, which is used for busses that
+	  have power domains and/or clocks which need to be enabled before use.
+
 config OF_TRANSLATE
 	bool "Translate addresses using fdt_translate_address"
 	depends on DM && OF_CONTROL