drm/amd/powerplay: update how to use metrics table on Arcturus

Retrieve only those interested metrics data instead of the whole
metrics table. By this, the memory copy can be dropped.

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