In some cases with Generic FLow, it is only required to show the pattern
of spec and mask, but no need to add the flow. Therefore, add an option
in packetforge so that users can show spec and mask only.
Type: improvement
Signed-off-by: Ting Xu <ting.xu@intel.com>
Change-Id: I7b3040689eb82d0b58924712ee6fc9cfa0a42fa1