LU-7732 ldlm: silence verbose "waking for gap" log messages

LU-7732 ldlm: silence verbose "waking for gap" log messages

Quiet down the very frequent and not very useful
"waking for gap in transno" error messages that fill up
the log under certain conditions.

Signed-off-by: Bob Glossman <bob.glossman@intel.com>
Change-Id: I8264a958fa030ef66a3752dbf6e58ba79130d4b7
Reviewed-on: http://review.whamcloud.com/21418
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>