Merge pull request #4969 from Chili-Man/bugfix/aws_provider_rds_security_groups

provider/aws: apply security group changes in EC2 Classic RDS for aws_db_instance

builtin/providers/aws/resource_aws_db_instance.go

@@ -775,7 +775,7 @@ func resourceAwsDbInstanceUpdate(d *schema.ResourceData, meta interface{}) error
 		requestUpdate = true
 	}
 
-	if d.HasChange("vpc_security_group_ids") {
+	if d.HasChange("security_group_names") {
 		if attr := d.Get("security_group_names").(*schema.Set); attr.Len() > 0 {
 			var s []*string
 			for _, v := range attr.List() {