reduce polling and resume overhead by checking if inflight request exists
reduce polling and resume overhead by checking if inflight request exists

Change-Id: I0777a00f0cc082bab3348be8ec0be39faa50ffed
Signed-off-by: Ping Yu <7ad42b0e23f558553a923ffd1f1105b254082d9f@intel.com>

FDio/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,vpp-dev/vpp,vpp-dev/vpp,vpp-dev/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp