Fix pylint warning for files under `pynative_mode` directory.

tests/ut/python/pynative_mode/test_backend.py

@@ -24,7 +24,7 @@ from mindspore.common.parameter import Parameter
 from mindspore.ops import operations as P
 
 
-def setup_module(module):
+def setup_module():
     context.set_context(mode=context.PYNATIVE_MODE)
 
 

tests/ut/python/pynative_mode/test_bprop.py

@@ -24,7 +24,7 @@ from mindspore.ops import operations as P
 from ....mindspore_test_framework.utils.bprop_util import bprop
 
 
-def setup_module(module):
+def setup_module():
     context.set_context(mode=context.PYNATIVE_MODE)
 
 

tests/ut/python/pynative_mode/test_cell_bprop.py

@@ -219,7 +219,7 @@ class OneInputBprop(nn.Cell):
         return self.op(x)
 
     def bprop(self, x, out, dout):
-        return 5 * x,
+        return (5 * x,)
 
 
 def test_grad_one_input_bprop():
@@ -349,7 +349,7 @@ class MulAddWithWrongOutputNum(nn.Cell):
         return 2 * x + y
 
     def bprop(self, x, y, out, dout):
-        return 2 * dout,
+        return (2 * dout,)
 
 
 def test_grad_mul_add_with_wrong_output_num():