Fix bug in configure 'pcap drop trace on file xx.cap' command (VPP-691)
Fix bug in configure 'pcap drop trace on file xx.cap' command (VPP-691)

Change-Id: Id9cc1fbe18099fae483a823dc7c2b16d6bc46a8c
Signed-off-by: jerryian <4a3bb7211fea02b26260726cf085d22454192c54@zte.com.cn>

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