selftests/net: toeplitz: fix udp option

selftests/net: toeplitz: fix udp option

BugLink: https://bugs.launchpad.net/bugs/1956302
[ Upstream commit a8d13611b4a7b1b20d17bf2b9a89a3efcabde56c ]

Tiny fix. Option -u ("use udp") does not take an argument.

It can cause the next argument to silently be ignored.

Fixes: 5ebfb4cc3048 ("selftests/net: toeplitz test")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>