fib_rules: FRA_GENERIC_POLICY updates for ip proto, sport and dport attrs

Fixes: bfff4862 ("net: fib_rules: support for match on ip_proto, sport and dport")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>