net: phy: micrel: fix interrupt handling

After migration to the shared interrupt support, the KSZ8031 PHY with
enabled interrupt support was not able to notify about link status
change.

Fixes: 59ca4e58

 ("net: phy: micrel: implement generic .handle_interrupt() callback")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20201127123621.31234-1-o.rempel@pengutronix.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>