Revert "drm/amdgpu: change the reference clock for raven/raven2"

This reverts commit fbc24293.

This results in inconsistent timing reported via asynchronous
GPU queries.

Link: https://lists.freedesktop.org/archives/amd-gfx/2023-May/093731.html


Cc: Jesse.Zhang@amd.com
Cc: michel@daenzer.net
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>