Use <mdio>:<addr>:<speed> trigger instead of netdev(link) trigger for
Fortinet FortiGate 50E, to indicate link speed on the each phys.
1000 Mbps: Green
100 Mbps : Amber
10 Mbps : (turn off)
Fixes: 102dc5a62506 ("mvebu: add support for Fortinet FortiGate 50E")
Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>