drm/ttm: export ttm_pool_fini for cleanup

ttm_pool_init is exported and used outside of ttm subsystem with
amdgpu_ttm interface, similarly export ttm_pool_fini for proper cleanup.
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_pool.c

@@ -600,6 +600,7 @@ void ttm_pool_fini(struct ttm_pool *pool)
 	 */
 	synchronize_shrinkers();
 }
+EXPORT_SYMBOL(ttm_pool_fini);
 
 /* As long as pages are available make sure to release at least one */
 static unsigned long ttm_pool_shrinker_scan(struct shrinker *shrink,