LU-1095 ofd: Silence 'slow create' warnings

LU-1095 ofd: Silence 'slow create' warnings

These messages were originally added to analyze a performance issue.
That issue is now much better understand and no longer needs to
be logged so verbosely.  They probably should have been disabled
prior to Lustre 2.4 being released but this was overlooked.

Change-Id: I395de36cdccc82afd4ed7b9c424d12d17b881f54
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-on: http://review.whamcloud.com/10394
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>