regulator: mc13xxx: Remove extern function declaration for mc13xxx_sw_regulator

This function does not exist, remove the extern function declaration.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/mc13xxx.h

@@ -32,7 +32,6 @@ struct mc13xxx_regulator_priv {
 	struct regulator_dev *regulators[];
 };
 
-extern int mc13xxx_sw_regulator(struct regulator_dev *rdev);
 extern int mc13xxx_fixed_regulator_set_voltage(struct regulator_dev *rdev,
 		int min_uV, int max_uV, unsigned *selector);
 extern int mc13xxx_fixed_regulator_get_voltage(struct regulator_dev *rdev);