regulator: Add REGULATOR_STATUS_UNDEFINED.

REGULATOR_STATUS_UNDEFINED is to be returned by regulator, if any other state
doesn't really apply.

Signed-off-by: Krystian Garbaciak <krystian.garbaciak@diasemi.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 8022638..2513a54 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -32,6 +32,8 @@
 	REGULATOR_STATUS_NORMAL,
 	REGULATOR_STATUS_IDLE,
 	REGULATOR_STATUS_STANDBY,
+	/* in case that any other status doesn't apply */
+	REGULATOR_STATUS_UNDEFINED,
 };
 
 /**