net: bcmgenet: Support wake-up from s2idle

net: bcmgenet: Support wake-up from s2idle

When we suspend into s2idle we also need to enable the interrupt line
that generates the MPD and HFB interrupts towards the host CPU interrupt
controller (typically the ARM GIC or MIPS L1) to make it exit s2idle.

When we suspend into other modes such as "standby" or "mem" we engage a
power management state machine which will gate off the CPU L1 controller
(priv->irq0) and ungate the side band wake-up interrupt (priv->wol_irq).
It is safe to have both enabled as wake-up sources because they are
mutually exclusive given any suspend mode.

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