drm/nouveau/ttm: fix crash as a result of a recent ttm change

"drm/ttm: callback move_notify any time bo placement change v4" failed to
avoid a NULL pointer dereference in nouveau caused by move_notify being
expected to handle that case now.

Signed-off-by: Ben Skeggs <[e-mail]>

drivers/gpu/drm/nouveau/nouveau_bo.c

···
 	if (mem->mem_type == TTM_PL_VRAM)
 		nouveau_vm_map(vma, node);
 	else
-		nouveau_vm_map_sg(vma, 0, mem->num_pages << PAGE_SHIFT,
-				  node, node->pages);
+		nouveau_vm_map_sg(vma, 0, mem->num_pages << PAGE_SHIFT, node);
 
 	return 0;
 }
···
 static void
 nouveau_bo_move_ntfy(struct ttm_buffer_object *bo, struct ttm_mem_reg *new_mem)
 {
-	struct nouveau_mem *node = new_mem->mm_node;
 	struct nouveau_bo *nvbo = nouveau_bo(bo);
 	struct nouveau_vma *vma;
 
···
 		    nvbo->page_shift == vma->vm->spg_shift) {
 			nouveau_vm_map_sg(vma, 0, new_mem->
 					  num_pages << PAGE_SHIFT,
-					  node, node->pages);
+					  new_mem->mm_node);
 		} else {
 			nouveau_vm_unmap(vma);
 		}
···
 		nouveau_vm_map(vma, nvbo->bo.mem.mm_node);
 	else
 	if (nvbo->bo.mem.mem_type == TTM_PL_TT)
-		nouveau_vm_map_sg(vma, 0, size, node, node->pages);
+		nouveau_vm_map_sg(vma, 0, size, node);
 
 	list_add_tail(&vma->head, &nvbo->vma_list);
 	vma->refcount = 1;

drivers/gpu/drm/nouveau/nouveau_vm.c

···
 
 void
 nouveau_vm_map_sg(struct nouveau_vma *vma, u64 delta, u64 length,
-		  struct nouveau_mem *mem, dma_addr_t *list)
+		  struct nouveau_mem *mem)
 {
 	struct nouveau_vm *vm = vma->vm;
+	dma_addr_t *list = mem->pages;
 	int big = vma->node->type != vm->spg_shift;
 	u32 offset = vma->node->offset + (delta >> 12);
 	u32 bits = vma->node->type - 12;

drivers/gpu/drm/nouveau/nouveau_vm.h

···
 void nouveau_vm_unmap(struct nouveau_vma *);
 void nouveau_vm_unmap_at(struct nouveau_vma *, u64 offset, u64 length);
 void nouveau_vm_map_sg(struct nouveau_vma *, u64 offset, u64 length,
-		       struct nouveau_mem *, dma_addr_t *);
+		       struct nouveau_mem *);
 
 /* nv50_vm.c */
 void nv50_vm_map_pgt(struct nouveau_gpuobj *pgd, u32 pde,