gfs2: Remove the QUOTA_USER and QUOTA_GROUP defines

Remove the QUOTA_USER and QUOTA_GRUP defines.  Remove
the last vestigal users of QUOTA_USER and QUOTA_GROUP.

Now that struct kqid is used throughout the gfs2 quota
code the need there is to use QUOTA_USER and QUOTA_GROUP
and the defines are just extraneous and confusing.

Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>