cpupower: Update family checks when decoding HW pstates

The family checks in get_cof() and get_did() need to use the
correct MSR format depending on the family. Add a cpupower
capability for using the pstatedef (family 17h and newer) to
control this instead of direct family checks.

Signed-off-by: Nathan Fontenot <nathan.fontenot@amd.com>
Reviewed-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>