monitor: removed cpustats command

monitor: removed cpustats command

Since ppc was the last architecture to collect these statistics and
it is currently phasing this collection out, the command that would query
this information is being removed.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Bruno Larsen (billionai) <bruno.larsen@eldorado.org.br>
Message-Id: <20210526202104.127910-5-bruno.larsen@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>