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: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 11ee6ec7..53cbd16 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -496,6 +496,7 @@
 	 of the device
 
 config MFD_ARIZONA
+	select REGMAP
 	tristate
 
 config MFD_ARIZONA_I2C