bpf, x86_64: Fail gracefully on bpf_jit_binary_pack_finalize failures

Instead of BUG_ON(), fail gracefully and return orig_prog.

Fixes: 1022a549 ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220208062533.3802081-1-song@kernel.org