NAT64: Fix error message typo (VPP-961)
NAT64: Fix error message typo (VPP-961)

Change-Id: Ieb81c5e157e342cbb532bd65f3b64059e5838691
Signed-off-by: Matus Fabian <fce541bb5d92358522a3d9dac9c8f88030b6f773@cisco.com>

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