davinci: Add CONFIG_REGULATOR_DUMMY to DA8XX defconfig file.

In order to support reference DA8XX machines not providing a
voltage regulator control for the core voltage, the REGULATOR_DUMMY
option is required.

Signed-off-by: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/configs/da8xx_omapl_defconfig

@@ -79,6 +79,7 @@ CONFIG_I2C_DAVINCI=y
 # CONFIG_HWMON is not set
 CONFIG_WATCHDOG=y
 CONFIG_REGULATOR=y
+CONFIG_REGULATOR_DUMMY=y
 CONFIG_REGULATOR_TPS6507X=y
 CONFIG_FB=y
 CONFIG_FB_DA8XX=y