btrfs: tree-checker: use %zu format string for size_t

The return value of sizeof() is of type size_t, so we must print it
using the %z format modifier rather than %l to avoid this warning
on some architectures:

fs/btrfs/tree-checker.c: In function 'check_dir_item':
fs/btrfs/tree-checker.c:273:50: error: format '%lu' expects argument of type 'long unsigned int', but argument 5 has type 'u32' {aka 'unsigned int'} [-Werror=format=]

Fixes: 005887f2e3e0 ("btrfs: tree-checker: Add checker for dir item")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/tree-checker.c

@@ -270,7 +270,7 @@ static int check_dir_item(struct btrfs_root *root,
 		/* header itself should not cross item boundary */
 		if (cur + sizeof(*di) > item_size) {
 			dir_item_err(root, leaf, slot,
-		"dir item header crosses item boundary, have %lu boundary %u",
+		"dir item header crosses item boundary, have %zu boundary %u",
 				cur + sizeof(*di), item_size);
 			return -EUCLEAN;
 		}