net: bcmgenet: suspend and resume from Wake-on-LAN

Update bcmgenet_suspend() to prepare the hardware for being put into
Wake-on-LAN mode if the device can wakeup the system, and Wake-on-LAN is
enabled. Whether we resume from Wake-on-LAN or not, make sure that
bcmgenet_resume() disables the UniMAC MagicPacket matching mode and puts
the hardware in a state where it can receive all incoming packets.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>