Add support for using GPIO interrupts with a fixed-link GPIO rather than
polling the GPIO every second and invoking the phylink resolution.  This
avoids unnecessary calls to mac_config().
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>