bpf set fib_params just before bpf_fib_lookup
bpf set fib_params just before bpf_fib_lookup

Also fixes fib_params->tot_len as it is taken from the final ip header

fixes BPF-231

neiljerram/felix,neiljerram/felix,neiljerram/felix,Metaswitch/calico,neiljerram/felix,Metaswitch/calico