ice: use ice_down_up() where applicable

ice_change_mtu() is currently using a separate ice_down() and ice_up()
calls to reflect changed MTU. ice_down_up() serves this purpose, so do
the refactoring here.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_main.c

@@ -7412,21 +7412,9 @@ static int ice_change_mtu(struct net_device *netdev, int new_mtu)
 	}
 
 	netdev->mtu = (unsigned int)new_mtu;
-
-	/* if VSI is up, bring it down and then back up */
-	if (!test_and_set_bit(ICE_VSI_DOWN, vsi->state)) {
-		err = ice_down(vsi);
-		if (err) {
-			netdev_err(netdev, "change MTU if_down err %d\n", err);
-			return err;
-		}
-
-		err = ice_up(vsi);
-		if (err) {
-			netdev_err(netdev, "change MTU if_up err %d\n", err);
-			return err;
-		}
-	}
+	err = ice_down_up(vsi);
+	if (err)
+		return err;
 
 	netdev_dbg(netdev, "changed MTU to %d\n", new_mtu);
 	set_bit(ICE_FLAG_MTU_CHANGED, pf->flags);