bpf: Do per-instruction state dumping in verifier when log_level > 1.

If log_level > 1, do a state dump every instruction and emit it in
a more compact way (without a leading newline).

This will facilitate more sophisticated test cases which inspect the
verifier log for register state.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>