Fixes for tensorflow#9664 (#2711)

Author: ekuznetsov139

tensorflow/core/kernels/reduction_gpu_kernels.cu.h

@@ -725,7 +725,7 @@ inline bool isGfx10orGfx11(OpKernelContext* ctx) {
   result = hipGetDeviceProperties(&props, dev);
   if (result == hipSuccess) {
     std::string gcnArchName = props.gcnArchName;
-    return (gcnArchName.substr(0,5)=="gfx10" || gcnArchName.substr(0,5)=="gfx11");
+    return gcnArchName.substr(0,4)=="gfx1";
   }
   return false;
 }

tensorflow/core/util/gpu_launch_config.h

@@ -203,6 +203,8 @@ GpuLaunchConfig GetGpuLaunchConfigFixedBlockSize(
 #elif TENSORFLOW_USE_ROCM
   hipError_t err = hipOccupancyMaxActiveBlocksPerMultiprocessor(
       &block_count, func, fixed_block_size, dynamic_shared_memory_size);
+  if (block_count < 1)
+    block_count = 1;
   CHECK_EQ(err, hipSuccess);
 #endif
   block_count = std::min(block_count * d.getNumGpuMultiProcessors(),