mfd: add DB5500 PRCMU driver

This adds the DB5500 PRCMU driver. Right now this one is pretty
restricted in functionality, exposing a simple interface to send
I2C messages.

Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 7eaeb97..481770a 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -585,6 +585,16 @@
 	  system controller running an XP70 microprocessor, which is accessed
 	  through a register map.
 
+config MFD_DB5500_PRCMU
+	bool "ST-Ericsson DB5500 Power Reset Control Management Unit"
+	depends on UX500_SOC_DB5500
+	select MFD_CORE
+	help
+	  Select this option to enable support for the DB5500 Power Reset
+	  and Control Management Unit. This is basically an autonomous
+	  system controller running an XP70 microprocessor, which is accessed
+	  through a register map.
+
 config MFD_CS5535
 	tristate "Support for CS5535 and CS5536 southbridge core functions"
 	select MFD_CORE