drm/nouveau/dmem: empty chunk do not have a buffer object associated with them.

Empty chunk do not have a bo associated with them so no need to pin/unpin
on suspend/resume.

This fix suspend/resume on 5.1rc1 when NOUVEAU_SVM is enabled.
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Tested-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_dmem.c

@@ -454,11 +454,6 @@ nouveau_dmem_resume(struct nouveau_drm *drm)
 		/* FIXME handle pin failure */
 		WARN_ON(ret);
 	}
-	list_for_each_entry (chunk, &drm->dmem->chunk_empty, list) {
-		ret = nouveau_bo_pin(chunk->bo, TTM_PL_FLAG_VRAM, false);
-		/* FIXME handle pin failure */
-		WARN_ON(ret);
-	}
 	mutex_unlock(&drm->dmem->mutex);
 }
 
@@ -477,9 +472,6 @@ nouveau_dmem_suspend(struct nouveau_drm *drm)
 	list_for_each_entry (chunk, &drm->dmem->chunk_full, list) {
 		nouveau_bo_unpin(chunk->bo);
 	}
-	list_for_each_entry (chunk, &drm->dmem->chunk_empty, list) {
-		nouveau_bo_unpin(chunk->bo);
-	}
 	mutex_unlock(&drm->dmem->mutex);
 }