gre: clear IFF_TX_SKB_SHARING

ether_setup sets IFF_TX_SKB_SHARING but this is not supported by gre
as it modifies the skb on xmit.

Also, clean up whitespace in ipgre_tap_setup when we're already touching it.
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_gre.c

@@ -1055,6 +1055,7 @@ static void ipgre_tap_setup(struct net_device *dev)
 {
 	ether_setup(dev);
 	dev->netdev_ops	= &gre_tap_netdev_ops;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 	dev->priv_flags	|= IFF_LIVE_ADDR_CHANGE;
 	ip_tunnel_setup(dev, gre_tap_net_id);
 }

net/ipv6/ip6_gre.c

@@ -1512,6 +1512,7 @@ static void ip6gre_tap_setup(struct net_device *dev)
 	dev->destructor = ip6gre_dev_free;
 
 	dev->features |= NETIF_F_NETNS_LOCAL;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 }
 
 static int ip6gre_newlink(struct net *src_net, struct net_device *dev,