sky2: fix hang in napi_disable

If IRQ was never initialized, then calling napi_disable() would hang.
Add more bookkeeping to track whether IRQ was ever initialized.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/marvell/sky2.h b/drivers/net/ethernet/marvell/sky2.h
index 0af31b8..ff6f58b 100644
--- a/drivers/net/ethernet/marvell/sky2.h
+++ b/drivers/net/ethernet/marvell/sky2.h
@@ -2287,6 +2287,7 @@
 #define SKY2_HW_RSS_BROKEN	0x00000100
 #define SKY2_HW_VLAN_BROKEN     0x00000200
 #define SKY2_HW_RSS_CHKSUM	0x00000400	/* RSS requires chksum */
+#define SKY2_HW_IRQ_SETUP	0x00000800
 
 	u8	     	     chip_id;
 	u8		     chip_rev;