net: phy: smsc: Cope with hot-removal in interrupt handler

If reading the Interrupt Source Flag register fails with -ENODEV, then
the PHY has been hot-removed and the correct response is to bail out
instead of throwing a WARN splat and attempting to suspend the PHY.
The PHY should be stopped in due course anyway as the kernel
asynchronously tears down the device.

Tested-by: Oleksij Rempel <o.rempel@pengutronix.de> # LAN9514/9512/9500
Tested-by: Ferry Toth <fntoth@gmail.com> # LAN9514
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/smsc.c

@@ -91,7 +91,9 @@ static irqreturn_t smsc_phy_handle_interrupt(struct phy_device *phydev)
 
 	irq_status = phy_read(phydev, MII_LAN83C185_ISF);
 	if (irq_status < 0) {
-		phy_error(phydev);
+		if (irq_status != -ENODEV)
+			phy_error(phydev);
+
 		return IRQ_NONE;
 	}