vxlan: remove vni zero check and drop for COLLECT_METADATA

This patch drops the vni zero check for COLLECT_METADATA mode.
It is not really needed, vni zero is a valid vni.

Fixes: 3ad7a4b141eb ("vxlan: support fdb and learning in COLLECT_METADATA mode"
Reported-by: Joe Stringer <joe@ovn.org>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -1333,9 +1333,6 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 
 	vni = vxlan_vni(vxlan_hdr(skb)->vx_vni);
 
-	if ((vs->flags & VXLAN_F_COLLECT_METADATA) && !vni)
-		goto drop;
-
 	vxlan = vxlan_vs_find_vni(vs, vni);
 	if (!vxlan)
 		goto drop;