geneve: allow changing DF behavior after creation

Currently, trying to change the DF parameter of a geneve device does
nothing:

    # ip -d link show geneve1
    14: geneve1: <snip>
        link/ether <snip>
        geneve id 1 remote 10.0.0.1 ttl auto df set dstport 6081 <snip>
    # ip link set geneve1 type geneve id 1 df unset
    # ip -d link show geneve1
    14: geneve1: <snip>
        link/ether <snip>
        geneve id 1 remote 10.0.0.1 ttl auto df set dstport 6081 <snip>

We just need to update the value in geneve_changelink.

Fixes: a025fb5f ("geneve: Allow configuration of DF behaviour")
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Reviewed-by: NStefano Brivio <sbrivio@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/geneve.c

@@ -1649,6 +1649,7 @@ static int geneve_changelink(struct net_device *dev, struct nlattr *tb[],
 	geneve->collect_md = metadata;
 	geneve->use_udp6_rx_checksums = use_udp6_rx_checksums;
 	geneve->ttl_inherit = ttl_inherit;
+	geneve->df = df;
 	geneve_unquiesce(geneve, gs4, gs6);
 
 	return 0;