regulator: da9063: fix assignment of da9063_reg_matches to NULL

cppcheck detected an incorrect assignment:

 drivers/regulator/da9063-regulator.c:711]: (warning) Assignment
 of function parameter has no effect outside the function

the original code didn't do anything, instead, *da9063_reg_matches
needs to be set to NULL.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/regulator/da9063-regulator.c

@@ -709,7 +709,7 @@ static struct da9063_regulators_pdata *da9063_parse_regulators_dt(
 		struct platform_device *pdev,
 		struct of_regulator_match **da9063_reg_matches)
 {
-	da9063_reg_matches = NULL;
+	*da9063_reg_matches = NULL;
 	return ERR_PTR(-ENODEV);
 }
 #endif