hw/core/cpu: removed cpu_dump_statistics function

No more architectures set the pointer to dump_statistics, so there's no
point in keeping it, or the related cpu_dump_statistics function.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Bruno Larsen (billionai) <bruno.larsen@eldorado.org.br>
Message-Id: <20210526202104.127910-6-bruno.larsen@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20210531145629.21300-2-bruno.larsen@eldorado.org.br>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>