The mv88e6390 changes the monitor control register into the Monitor
and Management control, which is an indirection register to various
registers.

Add ops to set the CPU port and the ingress/egress port for both
register layouts, to global1
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>