regulator: Export regulator_is_supported_voltage()

It's part of the driver interface so should be available to modules.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index dbdebed6..6f7d411 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1787,6 +1787,7 @@
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(regulator_is_supported_voltage);
 
 static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 				     int min_uV, int max_uV)