igb: Add switch case for supported hardware to igb_ptp_remove.

PTP initialization is only done on supported parts, so remove needs
same checks or it will cause crashes on systems with igb devices that
don't support PTP.  This patch adds those checks to the exit function.
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/igb_ptp.c

@@ -330,7 +330,17 @@ void igb_ptp_init(struct igb_adapter *adapter)
 
 void igb_ptp_remove(struct igb_adapter *adapter)
 {
-	cancel_delayed_work_sync(&adapter->overflow_work);
+	switch (adapter->hw.mac.type) {
+	case e1000_i211:
+	case e1000_i210:
+	case e1000_i350:
+	case e1000_82580:
+	case e1000_82576:
+		cancel_delayed_work_sync(&adapter->overflow_work);
+		break;
+	default:
+		return;
+	}
 
 	if (adapter->ptp_clock) {
 		ptp_clock_unregister(adapter->ptp_clock);