ebpf: remove BPF_LL_OFF in nhoff offset

It fixes invalid parsing in with recent kernels and does
not affect older kernels.

ebpf/bypass_filter.c

@@ -207,7 +207,7 @@ static __always_inline int ipv6_filter(struct __sk_buff *skb)
  * \return 0 to drop packet out and -1 to accept it
  */
 int SEC("filter") hashfilter(struct __sk_buff *skb) {
-    __u32 nhoff = BPF_LL_OFF + ETH_HLEN;
+    __u32 nhoff = ETH_HLEN;
 
     skb->cb[0] = nhoff;
     switch (skb->protocol) {

ebpf/filter.c

@@ -39,7 +39,7 @@ struct bpf_map_def SEC("maps") ipv4_drop = {
 };
 
 int SEC("filter") hashfilter(struct __sk_buff *skb) {
-    __u32 nhoff = BPF_LL_OFF + ETH_HLEN;
+    __u32 nhoff = ETH_HLEN;
     __u32 ip = 0;
     __u32 *value;