x86/msr: Add AMD CPPC MSR definitions

AMD CPPC (Collaborative Processor Performance Control) function uses MSR
registers to manage the performance hints. So add the MSR register macro
here.

Signed-off-by: Huang Rui <ray.huang@amd.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>