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>

block/file-posix.c

@@ -1398,7 +1398,7 @@ static void raw_refresh_zoned_limits(BlockDriverState *bs, struct stat *st,
                                      Error **errp)
 {
     BDRVRawState *s = bs->opaque;
-    BlockZoneModel zoned;
+    BlockZoneModel zoned = BLK_Z_NONE;
     int ret;
 
     ret = get_sysfs_zoned_model(st, &zoned);