ixgbe: fix panic due to uninitialised pointer

Systems containing an 82599EB and running a backported driver from
upstream were panicing on boot.  It turns out hw->mac.ops.setup_sfp is
only set for 82599, so one should check to be sure that pointer is set
before continuing in ixgbe_sfp_config_module_task.  I verified by
inspection that the upstream driver has the same issue and also added a
check before the call in ixgbe_sfp_link_config.
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ixgbe/ixgbe_main.c

@@ -3728,6 +3728,7 @@ static void ixgbe_sfp_link_config(struct ixgbe_adapter *adapter)
 			 * We need to try and force an autonegotiation
 			 * session, then bring up link.
 			 */
+			if (hw->mac.ops.setup_sfp)
 				hw->mac.ops.setup_sfp(hw);
 			if (!(adapter->flags & IXGBE_FLAG_IN_SFP_LINK_TASK))
 				schedule_work(&adapter->multispeed_fiber_task);
@@ -5968,6 +5969,7 @@ static void ixgbe_sfp_config_module_task(struct work_struct *work)
 		unregister_netdev(adapter->netdev);
 		return;
 	}
+	if (hw->mac.ops.setup_sfp)
 		hw->mac.ops.setup_sfp(hw);
 
 	if (!(adapter->flags & IXGBE_FLAG_IN_SFP_LINK_TASK))