mfd: AB3550 core driver

This adds a core driver for the AB3550 mixed-signal circuit
found in the ST-Ericsson U300 platforms. This driver
is a singleton proxy for all access to the AB3550 sub
functionality drivers which can be added on top of this one:
RTC, regulators, battery and system power control, vibrator,
LEDs and an ALSA codec.

Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Signed-off-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 4b8ad04..4c684c1 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -64,6 +64,7 @@
 obj-$(CONFIG_AB3100_CORE)	+= ab3100-core.o
 obj-$(CONFIG_AB3100_OTP)	+= ab3100-otp.o
 obj-$(CONFIG_AB4500_CORE)	+= ab4500-core.o
+obj-$(CONFIG_AB3550_CORE)	+= ab3550-core.o
 obj-$(CONFIG_MFD_TIMBERDALE)    += timberdale.o
 obj-$(CONFIG_PMIC_ADP5520)	+= adp5520.o
 obj-$(CONFIG_LPC_SCH)		+= lpc_sch.o