VXLAN:small refactor to vxlan input
VXLAN:small refactor to vxlan input

Change-Id: I2e7e08e1de20ab57e3f899b080b90a3082219ae5
Signed-off-by: Eyal Bari <fc8b6df29e0d3cf2af21713ee0e85afadbf47bf8@cisco.com>

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