[XFS] Add xfs_icsb_sync_counters_locked for when m_sb_lock already held

Add a new xfs_icsb_sync_counters_locked for the case where m_sb_lock
is already taken and add a flags argument to xfs_icsb_sync_counters so
that xfs_icsb_sync_counters_flags is not needed.

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30917a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>