sky2: synchronize irq on remove

Need to make sure interrupt is not racing with unregister of
network device.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>

drivers/net/sky2.c

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index ea23da5..9b16c2a 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -3327,6 +3327,8 @@
 	del_timer_sync(&hw->idle_timer);
 
 	sky2_write32(hw, B0_IMSK, 0);
+	synchronize_irq(hw->pdev->irq);
+
 	dev0 = hw->dev[0];
 	dev1 = hw->dev[1];
 	if (dev1)