fix lint again

Author: Matthew

python/tvm/relay/transform/fake_quantization_to_integer.py

@@ -251,6 +251,7 @@ def clip(expr, type_map):
 
 @register_fake_quantization_to_integer("nn.relu")
 def relu(expr, type_map):
+    """Rewrite a relu op"""
     arg = expr.args[0]
     t = type_map[arg]
     scale_shape = infer_shape(t.scale)