tools: bpftool: use err() instead of info() if there are too many insns

Make error messages and return codes more consistent. Specifically,
replace the use of info() macro with err() when too many eBPF
instructions are received to be dumped, given that bpftool returns with
a non-null exit value in that case.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>