drm/amd/powerplay: correct current clock level label for Arcturus

For dpm disabled case, it's assumed the only one support clock
level is always current clock level.

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