selftests: net: remove dependency on ebpf tests

selftests: net: remove dependency on ebpf tests

[ Upstream commit 98cb12eb52a780e682bea8372fdb2912c08132dd ]

Several net tests requires an XDP program build under the ebpf
directory, and error out if such program is not available.

That makes running successful net test hard, let's duplicate into the
net dir the [very small] program, re-using the existing rules to build
it, and finally dropping the bogus dependency.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/28e7af7c031557f691dc8045ee41dd549dd5e74c.1706131762.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 4acffb66630a ("selftests: net: explicitly wait for listener ready")
Signed-off-by: Sasha Levin <sashal@kernel.org>