flow: fix ebpf protocol hash
flow: fix ebpf protocol hash

skydive-project/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive