Extend the existing MRP netlink attributes to allow to configure MRP
Interconnect:

IFLA_BRIDGE_MRP_IN_ROLE - the parameter type is br_mrp_in_role which
  contains the interconnect id, the ring id, the interconnect role(MIM
  or MIC) and the port ifindex that represents the interconnect port.

IFLA_BRIDGE_MRP_IN_STATE - the parameter type is br_mrp_in_state which
  contains the interconnect id and the interconnect state.

IFLA_BRIDGE_MRP_IN_TEST - the parameter type is br_mrp_start_in_test
  which contains the interconnect id, the interval at which to send
  MRP_InTest frames, how many test frames can be missed before declaring
  the interconnect ring open and the period which represents for how long
  to send MRP_InTest frames.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>