gfs2: Fold qd_fish into gfs2_quota_sync

The split between qd_fish() and gfs2_quota_sync() is rather unfortunate
as qd_fish() is repeatedly called to scan sdp->sd_quota_list only to
find the next object to that needs syncing; if there are multiple
objects on the list that need syncing, it makes more sense to grab them
all in one go.  This is relatively easy to do when qd_fish() is folded
into gfs2_quota_sync().

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