Fix bug in configure 'vlan-strip-offload on' first, then configure "set interface mtu" command, vlan-strip-offload option will be changed to off.
Fix bug in configure 'vlan-strip-offload on' first, then configure "set interface mtu" command,
vlan-strip-offload option will be changed to off.

Change-Id: I1f39628fc8cde4e46ed5b2e3208253a07327de81
Signed-off-by: jerryian <4a3bb7211fea02b26260726cf085d22454192c54@zte.com.cn>

milanlenco/vpp,vpp-dev/vpp,vpp-dev/vpp,milanlenco/vpp,chrisy/vpp,FDio/vpp,GabrielGanne/vpp-flowtable,FDio/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,milanlenco/vpp,milanlenco/vpp,chrisy/vpp,GabrielGanne/vpp-flowtable,FDio/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,GabrielGanne/vpp-flowtable,vpp-dev/vpp,GabrielGanne/vpp-flowtable,chrisy/vpp,FDio/vpp,GabrielGanne/vpp-flowtable,milanlenco/vpp,GabrielGanne/vpp-flowtable,milanlenco/vpp,FDio/vpp