selftests/net: pass ipv6_args to udpgso_bench's IPv6 TCP test

udpgso_bench.sh has been running its IPv6 TCP test with IPv4 arguments
since its initial conmit. Looks like a typo.

Fixes: 3a687be ("selftests: udp gso benchmark")
Cc: willemb@google.com
Signed-off-by: Dimitris Michailidis <dmichail@fungible.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20220623000234.61774-1-dmichail@fungible.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/udpgso_bench.sh

@@ -120,7 +120,7 @@ run_all() {
 	run_udp "${ipv4_args}"
 
 	echo "ipv6"
-	run_tcp "${ipv4_args}"
+	run_tcp "${ipv6_args}"
 	run_udp "${ipv6_args}"
 }