mfd: Force on REGMAP for the arizona core

While the core isn't useful by itself it does depend on regmap so try to
force that on.
Reported-by: NMyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/Kconfig

@@ -496,6 +496,7 @@ config MFD_S5M_CORE
 	 of the device
 
 config MFD_ARIZONA
+	select REGMAP
 	tristate
 
 config MFD_ARIZONA_I2C