skge: protect interrupt mask

There is a race between updating the irq mask and setting it
which can be triggered on SMP with a bad cable.
Similar patch from Ingo Molnar and Thomas Gleixner

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
diff --git a/drivers/net/skge.h b/drivers/net/skge.h
index 2efdacc..941f12a 100644
--- a/drivers/net/skge.h
+++ b/drivers/net/skge.h
@@ -2402,6 +2402,7 @@
 
 	struct tasklet_struct ext_tasklet;
 	spinlock_t	     phy_lock;
+	spinlock_t	     hw_lock;
 };
 
 enum {