netdev-offload-tc: Expand tunnel source IPs masked match

netdev-offload-tc: Expand tunnel source IPs masked match

To support more use case, for example, DDOS, which
packets should be dropped in hardware, this patch
allows users to match only the tunnel source IPs with
masked value.

$ ovs-appctl dpctl/add-flow "tunnel(src=2.2.2.0/255.255.255.0,tp_dst=4789,ttl=64),\
  recirc_id(2),in_port(3),eth(),eth_type(0x0800),ipv4()" ""

$ ovs-appctl dpctl/dump-flows
  tunnel(src=2.2.2.0/255.255.255.0,ttl=64,tp_dst=4789) ... actions:drop
$ tc filter show dev vxlan_sys_4789 ingress
  ...
  eth_type ipv4
  enc_src_ip 2.2.2.0/24
  enc_dst_port 4789
  enc_ttl 64
  in_hw in_hw_count 2
    action order 1: gact action drop
    ...

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>