cpufreq: amd-pstate: Expose struct amd_cpudata

Expose struct amd_cpudata to AMD P-State unit test module.

This data struct will be used on the following AMD P-State unit test
(amd-pstate-ut) module. The amd-pstate-ut module can get some
AMD infomations by this data struct. For example: highest perf,
nominal perf, boost supported etc.

Signed-off-by: Meng Li <li.meng@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>