Fix GOOGLE_CUDA=1 flag (#460)

Author: WindQAQ

tensorflow_addons/custom_ops/activations/cc/kernels/gelu_op.cc

@@ -36,7 +36,7 @@ using CPUDevice = Eigen::ThreadPoolDevice;
 TF_CALL_GPU_NUMBER_TYPES(REGISTER_GELU_KERNELS);
 #undef REGISTER_GELU_KERNELS
 
-#ifdef GOOGLE_CUDA
+#if GOOGLE_CUDA
 
 using GPUDevice = Eigen::GpuDevice;
 

tensorflow_addons/custom_ops/layers/cc/kernels/correlation_cost_op.cc

@@ -331,7 +331,7 @@ TF_CALL_float(REGISTER_CORRELATIONCOST_OP_CPU);
 #undef REGISTER_CORRELATIONCOST_OP_CPU
 
 // Register the GPU kernels.
-#ifdef GOOGLE_CUDA
+#if GOOGLE_CUDA
 
 #define REGISTER_CORRELATIONCOST_OP_GPU(T)                                   \
   REGISTER_KERNEL_BUILDER(                                                   \