This is the implementation of CFM netlink status
get information interface.

Add new nested netlink attributes. These attributes are used by the
user space to get status information.

GETLINK:
    Request filter RTEXT_FILTER_CFM_STATUS:
    Indicating that CFM status information must be delivered.

    IFLA_BRIDGE_CFM:
        Points to the CFM information.

    IFLA_BRIDGE_CFM_MEP_STATUS_INFO:
        This indicate that the MEP instance status are following.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_INFO:
        This indicate that the peer MEP status are following.

CFM nested attribute has the following attributes in next level.

GETLINK RTEXT_FILTER_CFM_STATUS:
    IFLA_BRIDGE_CFM_MEP_STATUS_INSTANCE:
        The MEP instance number of the delivered status.
        The type is u32.
    IFLA_BRIDGE_CFM_MEP_STATUS_OPCODE_UNEXP_SEEN:
        The MEP instance received CFM PDU with unexpected Opcode.
        The type is u32 (bool).
    IFLA_BRIDGE_CFM_MEP_STATUS_VERSION_UNEXP_SEEN:
        The MEP instance received CFM PDU with unexpected version.
        The type is u32 (bool).
    IFLA_BRIDGE_CFM_MEP_STATUS_RX_LEVEL_LOW_SEEN:
        The MEP instance received CCM PDU with MD level lower than
        configured level. This frame is discarded.
        The type is u32 (bool).

    IFLA_BRIDGE_CFM_CC_PEER_STATUS_INSTANCE:
        The MEP instance number of the delivered status.
        The type is u32.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_PEER_MEPID:
        The added Peer MEP ID of the delivered status.
        The type is u32.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_CCM_DEFECT:
        The CCM defect status.
        The type is u32 (bool).
        True means no CCM frame is received for 3.25 intervals.
        IFLA_BRIDGE_CFM_CC_CONFIG_EXP_INTERVAL.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_RDI:
        The last received CCM PDU RDI.
        The type is u32 (bool).
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_PORT_TLV_VALUE:
        The last received CCM PDU Port Status TLV value field.
        The type is u8.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_IF_TLV_VALUE:
        The last received CCM PDU Interface Status TLV value field.
        The type is u8.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_SEEN:
        A CCM frame has been received from Peer MEP.
        The type is u32 (bool).
        This is cleared after GETLINK IFLA_BRIDGE_CFM_CC_PEER_STATUS_INFO.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_TLV_SEEN:
        A CCM frame with TLV has been received from Peer MEP.
        The type is u32 (bool).
        This is cleared after GETLINK IFLA_BRIDGE_CFM_CC_PEER_STATUS_INFO.
    IFLA_BRIDGE_CFM_CC_PEER_STATUS_SEQ_UNEXP_SEEN:
        A CCM frame with unexpected sequence number has been received
        from Peer MEP.
        The type is u32 (bool).
        When a sequence number is not one higher than previously received
        then it is unexpected.
        This is cleared after GETLINK IFLA_BRIDGE_CFM_CC_PEER_STATUS_INFO.
Signed-off-by: Henrik Bjoernlund  <henrik.bjoernlund@microchip.com>
Reviewed-by: Horatiu Vultur  <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>