drm/ttm: Make LRU removal optional v2

We are already doing this for DMA-buf imports and also for
amdgpu VM BOs for quite a while now.

If this doesn't run into any problems we are probably going
to stop removing BOs from the LRU altogether.

v2: drop BUG_ON from ttm_bo_add_to_lru

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Tested-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

include/drm/ttm/ttm_execbuf_util.h

@@ -70,6 +70,7 @@ extern void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
  * @list:    thread private list of ttm_validate_buffer structs.
  * @intr:    should the wait be interruptible
  * @dups:    [out] optional list of duplicates.
+ * @del_lru: true if BOs should be removed from the LRU.
  *
  * Tries to reserve bos pointed to by the list entries for validation.
  * If the function returns 0, all buffers are marked as "unfenced",
@@ -98,7 +99,7 @@ extern void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
 
 extern int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
 				  struct list_head *list, bool intr,
-				  struct list_head *dups);
+				  struct list_head *dups, bool del_lru);
 
 /**
  * function ttm_eu_fence_buffer_objects.