drm/amd/display: Fix invalid Copyright notice

[Why && How]
Copyright notice failed in the Palamida scan and make changes to
align with our guidelines.

Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Leo Ma <hanghong.ma@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>