devlink: Add 'control' trap type

devlink: Add 'control' trap type

This type is used for traps that trap control packets such as ARP
request and IGMP query to the CPU.

Example:

# devlink -jp trap show netdevsim/netdevsim10 trap igmp_v1_report
{
    "trap": {
        "netdevsim/netdevsim10": [ {
                "name": "igmp_v1_report",
                "type": "control",
                "generic": true,
                "action": "trap",
                "group": "mc_snooping"
            } ]
    }
}

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>