[XFS] Re-initialize the per-cpu superblock counters after recovery.

After filesystem recovery the superblock is re-read to bring in any
changes. If the per-cpu superblock counters are not re-initialized from
the superblock then the next time the per-cpu counters are disabled they
might overwrite the global counter with a bogus value.

SGI-PV: 957348
SGI-Modid: xfs-linux-melb:xfs-kern:27999a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>