drm/vram-helper: Don't put new BOs into VRAM

Most drivers that use VRAM helpers have only a few MiB of framebuffer
memory available. To reduce fragmentation, new BOs are now put into
system memory by default. Only pin operations are allowed to move BOs
into VRAM.

v2:
	* rebased onto latest drm-tip
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200922145700.25413-4-tzimmermann@suse.de

drivers/gpu/drm/drm_gem_vram_helper.c

@@ -222,8 +222,7 @@ struct drm_gem_vram_object *drm_gem_vram_create(struct drm_device *dev,
 	acc_size = ttm_bo_dma_acc_size(bdev, size, sizeof(*gbo));
 
 	gbo->bo.bdev = bdev;
-	drm_gem_vram_placement(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM |
-			       DRM_GEM_VRAM_PL_FLAG_SYSTEM);
+	drm_gem_vram_placement(gbo, DRM_GEM_VRAM_PL_FLAG_SYSTEM);
 
 	/*
 	 * A failing ttm_bo_init will call ttm_buffer_object_destroy