selftests/bpf: Add fill_link_info test for perf event

Adding fill_link_info test for perf event and testing we
get its values back through the bpf_link_info interface.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-7-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>