bnxt: Add support for magic packet based Wake-on-LAN.

[venkatkumar.duvvuru_broadcom.com]

Summary

To enable WoL:-
sysctl dev.bnxt.<if_id>.wol=1

To disable WoL:-
sysctl dev.bnxt.<if_id>.wol=0

[sbruno]

In order for iflib and the network stack to know about WOL, you need to set the capabilities for WOL in the driver. I didn't see this done in this patch and I don't see it being done in the driver in the tree.

An example of what I'm referring to can be seen in sys/dev/e1000/if_em.c::2630

This lets the stack know that the WOL capabilities are enabled.

[venkatkumar.duvvuru_broadcom.com]

bnxt: Add support for magic packet based Wake-on-LAN.