drm/amd/pm: support runtime pptable update for sienna_cichlid etc.

This avoids smu issue when enabling runtime pptable update for
sienna_cichlid and so on. Runtime pptable udpate is needed for test
and debug purpose.

Signed-off-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>