Missing Identity Activation Import

Author: avik-pal

ext/NNlibCUDA/src/cudnn/activations.jl

@@ -4,7 +4,8 @@
 using Base.Broadcast
 using CUDA.CUDNN: cudnnActivationForward!, cudnnOpTensor!,
             CUDNN_ACTIVATION_TANH,CUDNN_ACTIVATION_SIGMOID,CUDNN_ACTIVATION_ELU,
-            CUDNN_ACTIVATION_RELU,CUDNN_ACTIVATION_CLIPPED_RELU,CUDNN_OP_TENSOR_MAX
+            CUDNN_ACTIVATION_RELU,CUDNN_ACTIVATION_CLIPPED_RELU,CUDNN_OP_TENSOR_MAX,
+            CUDNN_ACTIVATION_IDENTITY
 
 for (f, op) in [
     CUDA.tanh       => (src,dst)->cudnnActivationForward!(dst, src, mode=CUDNN_ACTIVATION_TANH),