net: phylib: fix interrupts re-enablement in phy_start

BugLink: https://bugs.launchpad.net/bugs/1785739

If phy was suspended and is starting, current driver always enable
phy's interrupts, if phy works in polling, phy can raise unexpected
interrupt which will not be handled, the interrupt will block system
enter suspend again. So interrupts should only be re-enabled if phy
works in interrupt.
Signed-off-by: Shaohui Xie <Shaohui.Xie@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 84a527a4)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/net/phy/phy.c

@@ -793,9 +793,11 @@ void phy_start(struct phy_device *phydev)
 		break;
 	case PHY_HALTED:
 		/* make sure interrupts are re-enabled for the PHY */
-		err = phy_enable_interrupts(phydev);
-		if (err < 0)
-			break;
+		if (phydev->irq != PHY_POLL) {
+			err = phy_enable_interrupts(phydev);
+			if (err < 0)
+				break;
+		}
 
 		phydev->state = PHY_RESUMING;
 		do_resume = true;