Revert "vxlan: fix tos value before xmit"

This reverts commit 71130f2.

In commit 71130f2 ("vxlan: fix tos value before xmit") we want to
make sure the tos value are filtered by RT_TOS() based on RFC1349.

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |   PRECEDENCE    |          TOS          | MBZ |
    +-----+-----+-----+-----+-----+-----+-----+-----+

But RFC1349 has been obsoleted by RFC2474. The new DSCP field defined like

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |          DS FIELD, DSCP           | ECN FIELD |
    +-----+-----+-----+-----+-----+-----+-----+-----+

So with

IPTOS_TOS_MASK          0x1E
RT_TOS(tos)		((tos)&IPTOS_TOS_MASK)

the first 3 bits DSCP info will get lost.

To take all the DSCP info in xmit, we should revert the patch and just push
all tos bits to ip_tunnel_ecn_encap(), which will handling ECN field later.

Fixes: 71130f2 ("vxlan: fix tos value before xmit")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: liuhangbin

drivers/net/vxlan.c

@@ -2740,7 +2740,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			goto out_unlock;
 		}
 
-		tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb);
+		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
 		err = vxlan_build_skb(skb, ndst, sizeof(struct iphdr),
 				      vni, md, flags, udp_sum);
@@ -2797,7 +2797,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			goto out_unlock;
 		}
 
-		tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb);
+		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip6_dst_hoplimit(ndst);
 		skb_scrub_packet(skb, xnet);
 		err = vxlan_build_skb(skb, ndst, sizeof(struct ipv6hdr),