test_bpf: flag tests that cannot be jited on s390

Flag with FLAG_EXPECTED_FAIL the BPF_MAXINSNS tests that cannot be jited
on s390 because they exceed BPF_SIZE_MAX and fail when
CONFIG_BPF_JIT_ALWAYS_ON is set. Also set .expected_errcode to -ENOTSUPP
so the tests pass in that case.

Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>