ocfs2: o2hb: increase unsteady iterations

When run multiple xattr test of ocfs2-test on a three-nodes cluster,
mount failed sometimes with the following message.

  o2hb: Unable to stabilize heartbeart on region D18B775E758D4D80837E8CF3D086AD4A (xvdb)

Stabilize heartbeat depends on the timing order to mount ocfs2 from
cluster nodes and how fast the tcp connections are established.  So
increase unsteady interations to leave more time for it.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>