bridge: mrp: Integrate MRP into the bridge

To integrate MRP into the bridge, the bridge needs to do the following:
- detect if the MRP frame was received on MRP ring port in that case it would be
  processed otherwise just forward it as usual.
- enable parsing of MRP
- before whenever the bridge was set up, it would set all the ports in
  forwarding state. Add an extra check to not set ports in forwarding state if
  the port is an MRP ring port. The reason of this change is that if the MRP
  instance initially sets the port in blocked state by setting the bridge up it
  would overwrite this setting.

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

net/bridge/br_input.c

@@ -342,6 +342,9 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 		}
 	}
 
+	if (unlikely(br_mrp_process(p, skb)))
+		return RX_HANDLER_PASS;
+
 forward:
 	switch (p->state) {
 	case BR_STATE_FORWARDING: