net: phy: broadcom: Add support for Wake-on-LAN

Add support for WAKE_UCAST, WAKE_MCAST, WAKE_BCAST, WAKE_MAGIC and
WAKE_MAGICSECURE. This is only supported with the BCM54210E and
compatible Ethernet PHYs. Using the in-band interrupt or an out of band
GPIO interrupts are supported.

Broadcom PHYs will generate a Wake-on-LAN level low interrupt on LED4 as
soon as one of the supported patterns is being matched. That includes
generating such an interrupt even if the PHY is operated during normal
modes. If WAKE_UCAST is selected, this could lead to the LED4 interrupt
firing up for every packet being received which is absolutely
undesirable from a performance point of view.

Because the Wake-on-LAN configuration can be set long before the system
is actually put to sleep, we cannot have an interrupt service routine to
clear on read the interrupt status register and ensure that new packet
matches will be detected.

It is desirable to enable the Wake-on-LAN interrupt as late as possible
during the system suspend process such that we limit the number of
interrupts to be handled by the system, but also conversely feed into
the Linux's system suspend way of dealing with interrupts in and around
the points of no return.

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>