bridge: uapi: mrp: Extend MRP_INFO attributes for interconnect status

Extend the existing MRP_INFO to return status of MRP interconnect. In
case there is no MRP interconnect on the node then the role will be
disabled so the other attributes can be ignored.

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>