geneve: fix incorrect setting of UDP checksum flag

Creating a geneve link with 'udpcsum' set results in a creation of link
for which UDP checksum will NOT be computed on outbound packets, as can
be seen below.

11: gen0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
    link/ether c2:85:27:b6:b4:15 brd ff:ff:ff:ff:ff:ff promiscuity 0
    geneve id 200 remote 192.168.13.1 dstport 6081 noudpcsum

Similarly, creating a link with 'noudpcsum' set results in a creation
of link for which UDP checksum will be computed on outbound packets.

Fixes: 9b4437a5b8 ("geneve: Unify LWT and netdev handling.")
Signed-off-by: Girish Moodalbail <girish.moodalbail@oracle.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Acked-by: Lance Richardson <lrichard@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/geneve.c

@@ -1244,7 +1244,7 @@ static int geneve_newlink(struct net *net, struct net_device *dev,
 		metadata = true;
 
 	if (data[IFLA_GENEVE_UDP_CSUM] &&
-	    !nla_get_u8(data[IFLA_GENEVE_UDP_CSUM]))
+	    nla_get_u8(data[IFLA_GENEVE_UDP_CSUM]))
 		info.key.tun_flags |= TUNNEL_CSUM;
 
 	if (data[IFLA_GENEVE_UDP_ZERO_CSUM6_TX] &&