migration: fix -Werror=maybe-uninitialized

migration: fix -Werror=maybe-uninitialized

../migration/savevm.c: In function ‘qemu_savevm_state_complete_precopy_non_iterable’:
../migration/savevm.c:1560:20: error: ‘ret’ may be used uninitialized [-Werror=maybe-uninitialized]
 1560 |             return ret;
      |                    ^~~

Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250114104811.2612846-1-marcandre.lureau@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>