f_flower: add cfm support

f_flower: add cfm support

Add support for matching on CFM Maintenance Domain level and opcode.

  # tc filter add dev ens6 ingress pref 1 proto cfm \
       flower cfm op 1 mdl 5 action ok

  # tc filter show dev ens6 ingress
    filter protocol cfm pref 1 flower chain 0
    filter protocol cfm pref 1 flower chain 0 handle 0x1
      eth_type 8902
      cfm mdl 5 op 1
      not_in_hw
            action order 1: gact action pass
             random type none pass val 0
             index 1 ref 1 bind 1

  # tc -j -p filter show dev ens6 ingress
    [ {
            "protocol": "cfm",
            "pref": 1,
            "kind": "flower",
            "chain": 0
        },{
            "protocol": "cfm",
            "pref": 1,
            "kind": "flower",
            "chain": 0,
            "options": {
                "handle": 1,
                "keys": {
                    "eth_type": "8902",
                    "cfm": {
                        "mdl": 5,
                        "op": 1
                    }
                },
                "not_in_hw": true,
                "actions": [ {
                        "order": 1,
                        "kind": "gact",
                        "control_action": {
                            "type": "pass"
                        },
                        "prob": {
                            "random_type": "none",
                            "control_action": {
                                "type": "pass"
                            },
                            "val": 0
                        },
                        "index": 1,
                        "ref": 1,
                        "bind": 1
                    } ]
            }
        } ]

Signed-off-by: Zahari Doychev <zdoychev@maxlinear.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>