lisp-cp: fix handling of ndp without source link addr VPP-1159
lisp-cp: fix handling of ndp without source link addr VPP-1159

Change-Id: Idddb60bbc7fcc701d39212f6422a6b2f6dc75221
Signed-off-by: Florin Coras <c9715e5cdf0718c2e9b10678757dfb027875eba2@cisco.com>
(cherry picked from commit cba3675fabe618194bf80a9de0e9c53b89a541ca)

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