drm/amd/powerplay: check before issuing messages for max sustainable clocks

Those messages are not supported on Arcturus and should not be
issued.

Affected ASIC: Arcturus

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>