xfs_repair: catch bad depth in traverse_int_dir2block

xfs_repair: catch bad depth in traverse_int_dir2block

A bad on-disk tree depth in traverse_int_dir2block() can
later cause a segfault when it's used as an array index in
this function; if we get something beyond the max depth,
just error out and the dir will get rebuilt.

Reported-by: Richard Kolkovich <richard@intrameta.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>