igb: cleanup usage of virtualization registers

The igb driver was incorrectly attempting to write to registers that do not
exist on 82580 hardware.  This wasn't causing any issues that I can tell,
but it is not recommended behavior either so I have changed this so we are
determining which registers to write to based on mac type.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/igb/igb_main.c

@@ -6137,19 +6137,23 @@ static void igb_vmm_control(struct igb_adapter *adapter)
 	struct e1000_hw *hw = &adapter->hw;
 	u32 reg;
 
-	/* replication is not supported for 82575 */
-	if (hw->mac.type == e1000_82575)
+	switch (hw->mac.type) {
+	case e1000_82575:
+	default:
+		/* replication is not supported for 82575 */
 		return;
-
-	/* enable replication vlan tag stripping */
-	reg = rd32(E1000_RPLOLR);
-	reg |= E1000_RPLOLR_STRVLAN;
-	wr32(E1000_RPLOLR, reg);
-
-	/* notify HW that the MAC is adding vlan tags */
-	reg = rd32(E1000_DTXCTL);
-	reg |= E1000_DTXCTL_VLAN_ADDED;
-	wr32(E1000_DTXCTL, reg);
+	case e1000_82576:
+		/* notify HW that the MAC is adding vlan tags */
+		reg = rd32(E1000_DTXCTL);
+		reg |= E1000_DTXCTL_VLAN_ADDED;
+		wr32(E1000_DTXCTL, reg);
+	case e1000_82580:
+		/* enable replication vlan tag stripping */
+		reg = rd32(E1000_RPLOLR);
+		reg |= E1000_RPLOLR_STRVLAN;
+		wr32(E1000_RPLOLR, reg);
+		break;
+	}
 
 	if (adapter->vfs_allocated_count) {
 		igb_vmdq_set_loopback_pf(hw, true);