block: fix -Werror=maybe-uninitialized false-positive

../block/file-posix.c:1405:17: error: ‘zoned’ may be used uninitialized [-Werror=maybe-uninitialized]
 1405 |     if (ret < 0 || zoned == BLK_Z_NONE) {

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
1 file changed