bpf: Add BPF_LD_IMM64 to the line_info test

This patch adds a BPF_LD_IMM64 case to the line_info test
to ensure the kernel rejects linfo_info.insn_off pointing
to the 2nd 8 bytes of the BPF_LD_IMM64.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>