drm/amd/display: Remove break after return

Remove break after return since it will never be reached.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>