submodule--helper: don't redundantly check "else if (res)"

The "res" variable must be true at this point in update_submodule(), as just a few lines above this we've unconditionally: if (!res) return 0; So we don't need to guard the "return 1" with an "else if (res)", we can return unconditionally at this point. See b3c5f5cb048 (submodule: move core cmd_update() logic to C, 2022-03-15) for the initial introduction of this code, this check of "res" has always been redundant. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Reviewed-by: Glen Choo <chooglen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>