btrfs: tree-checker: add missing return after error in root_item

There's a missing return statement after an error is found in the
root_item, this can cause further problems when a crafted image triggers
the error.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=210181
Fixes: 259ee775 ("btrfs: tree-checker: Add ROOT_ITEM check")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-checker.c

@@ -1068,6 +1068,7 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key,
 			    "invalid root item size, have %u expect %zu or %u",
 			    btrfs_item_size_nr(leaf, slot), sizeof(ri),
 			    btrfs_legacy_root_item_size());
+		return -EUCLEAN;
 	}
 
 	/*