schema/field: use actual go type in generated interfaces (#1428)

examples/privacyadmin/ent/user.go

@@ -29,9 +29,9 @@ func (*User) scanValues(columns []string) ([]interface{}, error) {
 	for i := range columns {
 		switch columns[i] {
 		case user.FieldID:
-			values[i] = &sql.NullInt64{}
+			values[i] = new(sql.NullInt64)
 		case user.FieldName:
-			values[i] = &sql.NullString{}
+			values[i] = new(sql.NullString)
 		default:
 			return nil, fmt.Errorf("unexpected column %q for type User", columns[i])
 		}