drm/amd/display: drop register logger and pid/tgid getters

While I'm sure this is useful I think we should bring it back later.

It's usage of pid/tgid is incorrect, you have to get/put
pid/tgids not store them away.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>