drm/amd/display: Fix stale buffer object (bo) use

Fixes stale buffer object (bo) usage for cursor plane

Cursor plane's bo operations are handled in DC code.
Currently, atomic_commit() does not handle bo operations
for cursor plane, as a result the bo assigned for cursor
plane in dm_plane_helper_prepare_fb() is not coherent
with the updates to the same made in dc code.This mismatch
leads to "bo" corruption and hence crashes during S3 entry.

This patch cleans up the code which was added as a hack
for 4.9 version only.

Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Pratik Vishwakarma <Pratik.Vishwakarma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3081,17 +3081,6 @@ static int dm_plane_helper_prepare_fb(struct drm_plane *plane,
 		}
 	}
 
-	/* It's a hack for s3 since in 4.9 kernel filter out cursor buffer
-	 * prepare and cleanup in drm_atomic_helper_prepare_planes
-	 * and drm_atomic_helper_cleanup_planes because fb doens't in s3.
-	 * IN 4.10 kernel this code should be removed and amdgpu_device_suspend
-	 * code touching fram buffers should be avoided for DC.
-	 */
-	if (plane->type == DRM_PLANE_TYPE_CURSOR) {
-		struct amdgpu_crtc *acrtc = to_amdgpu_crtc(new_state->crtc);
-
-		acrtc->cursor_bo = obj;
-	}
 	return 0;
 }