vmwgfx: Implement a proper GMR eviction mechanism

Use Ben's new range manager hooks to implement a manager for
GMRs that manages ids rather than ranges.
This means we can use the standard TTM code for binding, unbinding and
eviction.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
index e730418..41d9a5b 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
@@ -612,7 +612,6 @@
 {
 	struct ttm_buffer_object *bo = &vmw_bo->base;
 	struct ttm_placement ne_placement = vmw_vram_ne_placement;
-	struct drm_mm_node *mm_node;
 	int ret = 0;
 
 	ne_placement.lpfn = bo->num_pages;
@@ -626,9 +625,9 @@
 	if (unlikely(ret != 0))
 		goto err_unlock;
 
-	mm_node = bo->mem.mm_node;
 	if (bo->mem.mem_type == TTM_PL_VRAM &&
-	    mm_node->start < bo->num_pages)
+	    bo->mem.start < bo->num_pages &&
+	    bo->mem.start > 0)
 		(void) ttm_bo_validate(bo, &vmw_sys_placement, false,
 				       false, false);