ebpf: Return 0 when configuration fails

The kernel interprets the returned value as an unsigned 32-bit so -1
will mean queue 4294967295, which is awkward. Return 0 instead.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

tools/ebpf/rss.bpf.c

@@ -567,7 +567,7 @@ int tun_rss_steering_prog(struct __sk_buff *skb)
         return config->default_queue;
     }
 
-    return -1;
+    return 0;
 }
 
 char _license[] SEC("license") = "GPL v2";