bpf: remove obsolete prog->aux sanitation in bpf_insn_prepare_dump

This logic is not needed anymore since we got rid of the verifier
rewrite that was using prog->aux address in f6069b9a ("bpf:
fix redirect to map under tail calls").

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>