migration: vmstate_save_state_v(): fix error path

migration: vmstate_save_state_v(): fix error path

In case of pre_save_errp, on error, we continue processing fields,
unlike case of pre_save, where we return immediately. Behavior
for pre_save_errp case is wrong, we must return here, like for
pre_save.

 "migration: Add error-parameterized function variants in VMSD struct"

Fixes: 40de712a89
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Link: https://lore.kernel.org/r/20251028130738.29037-2-vsementsov@yandex-team.ru
Signed-off-by: Peter Xu <peterx@redhat.com>