[smoke-test] free iops

Change-Id: Ife2e44459c8726d31b99980015ec09806138c18f
Reviewed-on: http://review.couchbase.org/28200
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>