wireguard: coverity fix
wireguard: coverity fix

Type: fix

Change-Id: Ib69b9d83a77d315368ce091085b6bc2d26994282
Signed-off-by: Artem Glazychev <441b52f84e057ab1215b5caeaea1cdeb3a6be2f5@xored.com>

chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp