bridge: uapi: mrp: Fix MRP_PORT_ROLE

Currently the MRP_PORT_ROLE_NONE has the value 0x2 but this is in conflict
with the IEC 62439-2 standard. The standard defines the following port
roles: primary (0x0), secondary(0x1), interconnect(0x2).
Therefore remove the port role none.

Fixes: 4714d137

 ("bridge: uapi: mrp: Add mrp attributes.")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>