drm/amd/display: Added logging for automated DPM testing

drm/amd/display: Added logging for automated DPM testing

[Why]
Added clock logs to automate DPM testing

[How]
Added logs and helper functions to output clocks

Co-authored-by: Ryan Seto <ryanseto@amd.com>
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Ryan Seto <ryanseto@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>