nat: free port_bitmap
nat: free port_bitmap

Change-Id: Ied0fc50f1afb0f7fc563784544699726a6d03380
Signed-off-by: dongjuan <1b774497373669e00e0aec18f4d97e19aaab3049@zte.com.cn>

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