l2input: remove unused code and reduce number of branches
l2input: remove unused code and reduce number of branches

Change-Id: Ic37b5740285dc0020b9fdb0d8c98bc304cee7aa8
Signed-off-by: Damjan Marion <9141bba8b2efed526e55cf796d48631af330ad98@cisco.com>

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