service_linux: Fix null dereference in findLBEndpointSandbox
service_linux: Fix null dereference in findLBEndpointSandbox

Signed-off-by: Scott Percival <140d179b785839640e7d656a7089762bf56c2078@lastyard.com>

mahak/libnetwork,docker/libnetwork,mahak/libnetwork,docker/libnetwork,mahak/libnetwork,docker/libnetwork