drm/amd/display: Remove unnecessary files

[Why & How]
We accidentally upstream unnecessary files. Remove them.

Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>