This PR addresses 2 unit test failures introduced by the following commit
bd20260350
failing unit tests
```
//tensorflow/core/common_runtime/gpu:gpu_device_test
//tensorflow/core/common_runtime/gpu:gpu_device_unified_memory_test
```
It is different from PR #40164, which fixes the build error on the ROCm platform.
The commit above adds unit tests that check the assignment of priority values to GPU streams. Because ROCm support for assigning priority values to GPU streams is missing, those unit tests fail.
This PR/commit adds the missing ROCm support, and updates the unit test to work with AMD GPUs too. The valid priority value range seems to be different for AMD GPUs (0,2) as compared to NVidia GPUs (-1, 0), and hence the changes requrired in the testcases too.
856f899e4e