Remove useless code as the new back-end don't support older cudnn anywhere now.

theano/gpuarray/tests/test_dnn.py

@@ -1508,8 +1508,6 @@ def test_dnn_batchnorm_train_without_running_averages():
     # compile and run batch_normalization_train without running averages
     if not dnn.dnn_available(test_ctx_name):
         raise SkipTest(dnn.dnn_available.msg)
-    if dnn.version(raises=False) < 5000:
-        raise SkipTest("batch normalization requires cudnn v5+")
     utt.seed_rng()
 
     x, scale, bias, dy = T.tensor4('x'), T.tensor4('scale'), T.tensor4('bias'), T.tensor4('dy')
@@ -1593,8 +1591,6 @@ def test_dnn_batchnorm_train_inplace():
     # test inplace_running_mean and inplace_running_var
     if not dnn.dnn_available(test_ctx_name):
         raise SkipTest(dnn.dnn_available.msg)
-    if dnn.version(raises=False) < 5000:
-        raise SkipTest("batch normalization requires cudnn v5+")
     utt.seed_rng()
 
     x, scale, bias = T.tensor4('x'), T.tensor4('scale'), T.tensor4('bias')
@@ -1717,8 +1713,6 @@ def test_batchnorm_inference_inplace():
     # test inplace
     if not dnn.dnn_available(test_ctx_name):
         raise SkipTest(dnn.dnn_available.msg)
-    if dnn.version(raises=False) < 5000:
-        raise SkipTest("batch normalization requires cudnn v5+")
     utt.seed_rng()
 
     x, scale, bias, mean, var = (T.tensor4(n) for n in ('x', 'scale', 'bias', 'mean', 'var'))
@@ -1746,8 +1740,6 @@ def test_batchnorm_inference_inplace():
 def test_dnn_batchnorm_valid_and_invalid_axes():
     if not dnn.dnn_available(test_ctx_name):
         raise SkipTest(dnn.dnn_available.msg)
-    if dnn.version(raises=False) < 5000:
-        raise SkipTest("batch normalization requires cudnn v5+")
 
     for vartype in (T.tensor5, T.tensor4, T.tensor3, T.matrix):
         x, scale, bias, mean, var, dy = (vartype(n)