cpupower: Add function to print AMD P-State performance capabilities

AMD P-State kernel module is using the fine grain frequency instead of
acpi hardware pstate. So add a function to print performance and
frequency values.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>