drm/amd/powerplay: avoid frequent metrics table export

That's unnecessary. Also it makes more sense to show all the clocks
on one metrics table export.

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>