mfd: AB8500 register access via PRCMU I2C

This patch adds the choice of accessing the AB8500 registers
via prcmu I2C. Access either via SPI or I2C is supported.

Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index f771c52..d5968cd 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -69,6 +69,7 @@
 obj-$(CONFIG_AB3100_OTP)	+= ab3100-otp.o
 obj-$(CONFIG_AB3550_CORE)	+= ab3550-core.o
 obj-$(CONFIG_AB8500_CORE)	+= ab8500-core.o ab8500-spi.o
+obj-$(CONFIG_AB8500_I2C_CORE)	+= ab8500-i2c.o
 obj-$(CONFIG_AB8500_DEBUG)	+= ab8500-debugfs.o
 obj-$(CONFIG_MFD_TIMBERDALE)    += timberdale.o
 obj-$(CONFIG_PMIC_ADP5520)	+= adp5520.o