mfd: Add TPS6586x driver

Add mfd core driver for TPS6586x PMICs family.
The driver provides I/O access for the sub-device drivers and performs
regstration of the sub-devices based on the platform requirements.
In addition it implements GPIOlib interface for the chip GPIOs.

TODO:
        - add interrupt support
        - add platform data for PWM, backlight leds and charger

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Mike Rapoport <mike.rapoport@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index cc7cce0..1e48d7e 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -74,3 +74,4 @@
 obj-$(CONFIG_MFD_RDC321X)	+= rdc321x-southbridge.o
 obj-$(CONFIG_MFD_JANZ_CMODIO)	+= janz-cmodio.o
 obj-$(CONFIG_MFD_JZ4740_ADC)	+= jz4740-adc.o
+obj-$(CONFIG_MFD_TPS6586X)	+= tps6586x.o