gfs2: Revert "Add quota_change type"

gfs2: Revert "Add quota_change type"

Commit 432928c93779 ("gfs2: Add quota_change type") makes the incorrect
assertion that function do_qc() should behave differently in the two
contexts it is used in, but that isn't actually true.  In all cases,
do_qc() grabs a "reference" when it starts using a slot in the per-node
quota changes file, and it releases that "reference" when no more
residual changes remain.  Revert that broken commit.

There are some remaining issues with function do_qc() which are
addressed in the next commit.

This reverts commit 432928c9377959684c748a9bc6553ed2d3c2ea4f.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>