Arm backend: fix after resolving conflict

Change-Id: Iee6ae28e98d2a8bdb1e45347a9bf9a8cb31020a9

Author: wwwind

backends/arm/tosa/backend.py

@@ -161,7 +161,6 @@ def _sort_key(t: Node) -> int:
             graph_module.graph.lint()
             graph_module.recompile()
 
-        node_visitors = get_node_visitors(edge_program, tosa_spec)
         input_count = 0
         for node in graph_module.graph.nodes:
             node = cast(Node, node)