Revert "drm/amd/display: Implement zpos property"

This reverts commit 5b29369.

This patch causes IGT test case 'kms_atomic@plane-immutable-zpos' to
fail on AMDGPU hardware.

Cc: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Nicholas Choi <Nicholas.Choi@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c

@@ -1468,15 +1468,6 @@ int amdgpu_dm_plane_init(struct amdgpu_display_manager *dm,
 		drm_plane_create_blend_mode_property(plane, blend_caps);
 	}
 
-	if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
-		drm_plane_create_zpos_immutable_property(plane, 0);
-	} else if (plane->type == DRM_PLANE_TYPE_OVERLAY) {
-		unsigned int zpos = 1 + drm_plane_index(plane);
-		drm_plane_create_zpos_property(plane, zpos, 1, 254);
-	} else if (plane->type == DRM_PLANE_TYPE_CURSOR) {
-		drm_plane_create_zpos_immutable_property(plane, 255);
-	}
-
 	if (plane->type == DRM_PLANE_TYPE_PRIMARY &&
 	    plane_cap &&
 	    (plane_cap->pixel_format_support.nv12 ||