net: bcmgenet: Move wake-up event out of side band ISR

The side band interrupt service routine is not available on chips
like 7211, or rather, it does not permit the signaling of wake-up
events due to the complex interrupt hierarchy.

Move the wake-up event accounting into a .resume_noirq function,
account for possible wake-up events and clear the MPD/HFB interrupts
from there, while leaving the hardware untouched until the resume
function proceeds with doing its usual business.

Because bcmgenet_wol_power_down_cfg() now enables the MPD and HFB
interrupts, it is invoked by a .suspend_noirq function to prevent
the servicing of interrupts after the clocks have been disabled.

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