This reverts:
  commit 
33c133cc7598 ("phy: IRQ cannot be shared")
On hardware with multiple PHY devices hooked up to the same IRQ line, allow
them to share it.
Sergei Shtylyov says:
  "I'm not sure now what was the reason I concluded that the IRQ sharing
  was impossible... most probably I thought that the kernel IRQ handling
  code exited the loop over the IRQ actions once IRQ_HANDLED was returned
  -- which is obviously not so in reality..."
Signed-off-by: Xander Huff <xander.huff@ni.com>
Signed-off-by: Nathan Sullivan <nathan.sullivan@ni.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 int phy_start_interrupts(struct phy_device *phydev)
 {
        atomic_set(&phydev->irq_disable, 0);
-       if (request_irq(phydev->irq, phy_interrupt, 0, "phy_interrupt",
-                       phydev) < 0) {
+       if (request_irq(phydev->irq, phy_interrupt,
+                               IRQF_SHARED,
+                               "phy_interrupt",
+                               phydev) < 0) {
                pr_warn("%s: Can't get IRQ %d (PHY)\n",
                        phydev->mdio.bus->name, phydev->irq);
                phydev->irq = PHY_POLL;