add staticmethod for cudnn functions

theano/gpuarray/tests/test_dnn.py

@@ -2158,9 +2158,9 @@ def dconv2di(border_mode, subsample, filter_dilation, num_groups):
 
 class Cudnn_grouped_conv(Grouped_conv_noOptim):
     mode = mode_with_gpu
-    conv2d = dconv2d
-    conv2d_gradw = dconv2dw
-    conv2d_gradi = dconv2di
+    conv2d = staticmethod(dconv2d)
+    conv2d_gradw = staticmethod(dconv2dw)
+    conv2d_gradi = staticmethod(dconv2di)
     conv2d_op = dnn.GpuDnnConv
     conv2d_gradw_op = dnn.GpuDnnConvGradW
     conv2d_gradi_op = dnn.GpuDnnConvGradI