Like the ksz8081, the ksz9031 has the behavior where it will clear the
interrupt enable bits when leaving power down. This takes advantage of the
solution provided by f5aba91d

.

Signed-off-by: Xander Huff <xander.huff@ni.com>
Signed-off-by: Nathan Sullivan <nathan.sullivan@ni.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>