ocfs2: validate l_tree_depth to avoid out-of-bounds access

In the Linux kernel, the following vulnerability has been resolved: ocfs2: validate l_tree_depth to avoid out-of-bounds access The l_tree_depth field is 16-bit (__le16), but the actual maximum depth is limited to OCFS2_MAX_PATH_DEPTH. Add a check to prevent out-of-bounds access if l_tree_depth has an invalid value, which may occur when reading from a corrupted mounted disk [1].