drm/ttm: revert "add optional LRU removal callback v2"

Without the custom LRU management the callback is not used any more.

agd: fix trivial warning

Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-and-Tested-by: Roger.He <Hongbo.He@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

include/drm/ttm/ttm_bo_driver.h

@@ -462,12 +462,6 @@ struct ttm_bo_driver {
 			      struct ttm_mem_reg *mem);
 	void (*io_mem_free)(struct ttm_bo_device *bdev,
 			    struct ttm_mem_reg *mem);
-
-	/**
-	 * Optional driver callback for when BO is removed from the LRU.
-	 * Called with LRU lock held immediately before the removal.
-	 */
-	void (*lru_removal)(struct ttm_buffer_object *bo);
 };
 
 /**