bpf: add tls support for testing in test_sockmap

This adds a --ktls option to test_sockmap in order to enable the
combination of ktls and sockmap to run, which makes for another
batch of 648 test cases for both in combination.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>