[GFS2] gfs2_dinode_host fields are host-endian

Annotated scalar fields, dropped unused ones.  Note that
it's not at all obvious that we want to convert all of them
to host-endian...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>