tools: bpf_jit_disasm: increase image buffer size

JITed seccomp filters can be quite large if they check a lot of syscalls
Simply increase buffer size

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>