MB-100 Fix swaprebalance sleep call

Change-Id: I8b4e77ea51021c04c61ac50d4dd504766208ffc2
Reviewed-on: http://review.couchbase.org/25417
Reviewed-by: Deepkaran Salooja <deepkaran.salooja@globallogic.com>
Tested-by: Deepkaran Salooja <deepkaran.salooja@globallogic.com>