bpf: consolidate dumps to use bpf_dump_prog_info

bpf: consolidate dumps to use bpf_dump_prog_info

Consolidate dump of prog info to use bpf_dump_prog_info() when possible.
Moving forward, we want to have a consistent output for BPF progs when
being dumped. E.g. in cls/act case we used to dump tag as a separate
netlink attribute before we had BPF_OBJ_GET_INFO_BY_FD bpf(2) command.

Move dumping tag into bpf_dump_prog_info() as well, and only dump the
netlink attribute for older kernels. Also, reuse bpf_dump_prog_info()
for XDP case, so we can dump tag and whether program was jited, which
we currently don't show.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>