squashfs: Fix sqfs_inode_size() for xattr related SQFS_LSYMLINK_TYPE

squashfs: Fix sqfs_inode_size() for xattr related SQFS_LSYMLINK_TYPE

A squashfs filesystem with extended attributes (xattrs) may have
inodes of type SQFS_LSYMLINK_TYPE. This might cause u-boot to fail to
handle the filesystem since it assumes a SYMLINK_TYPE and LSYMLINK_TYPE
inode are the same size. This is wrong, see:
https://github.com/plougher/squashfs-tools/blob/master/squashfs-tools/read_fs.c#L421

Using the mksquashfs '-no-xattrs' argument is probably best, but the
mksquashfs '-xattrs' argument is the default.
This patch fixes squashfs image handling by making sure parsing the
uncompressed inode_table (with sqfs_find_inode) succeeeds. The only change
needed is correctly determining the size of a SQFS_LSYMLINK_TYPE inode.

Signed-off-by: Norbert van Bolhuis <nvbolhuis@gmail.com>