[XFS] Remove periodic logging of in-core superblock counters.

xfssyncd triggers the logging of superblock counters every 30s if the
filesystem is made with lazy-count=1. This will prevent disks from idling
and spinning down as there will be a log write every 30s. With the way
counter recovery works for lazy-count=1, this code is unnecessary and
provides no real benefit, so just remove it.

SGI-PV: 980145
SGI-Modid: xfs-linux-melb:xfs-kern:30840a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>