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/Makefile b/drivers/mfd/Makefile
index 814c57a..24aa444 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -79,6 +79,7 @@
 obj-$(CONFIG_MFD_DB8500_PRCMU)	+= db8500-prcmu.o
 # ab8500-i2c need to come after db8500-prcmu (which provides the channel)
 obj-$(CONFIG_AB8500_I2C_CORE)	+= ab8500-i2c.o
+obj-$(CONFIG_MFD_DB5500_PRCMU)	+= db5500-prcmu.o
 obj-$(CONFIG_MFD_TIMBERDALE)    += timberdale.o
 obj-$(CONFIG_PMIC_ADP5520)	+= adp5520.o
 obj-$(CONFIG_LPC_SCH)		+= lpc_sch.o