GFS2: Remove args subdir from gfs2 sysfs files

Since we can cat /proc/mounts there is no need to have this
subdirectory in the gfs2 sysfs files. In fact this does not
reflect the full range of possible mount argumenmts, where
as /proc/mounts does.

There was only one userland user of this set of sysfs files
and it will function perfectly well without these files
being present (in fact that subcommand of gfs2_tool is
obsolete anyway).

The tune/* subdirectory is also considered mostly obsolete,
but there are a few uses of this until mount arguments can
be added for the last few functions for which there are no
equivalents currently. However the tune/* directory is still
in my sights and new code should avoid using it. Only the gfs2_quota
and gfs2_tool programs are know to use tune/* at the moment.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>