gpu-compute: Add methods to read GPU memory requestor ID

These methods are called from various places to override the requestor
ID of a request in order to determine which Ruby network a request
should be routed on.

Change-Id: Ic0270ddd7123f0457a13144e69ef9132204d4334
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57651
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/gpu-compute/gpu_command_processor.hh

@@ -76,6 +76,7 @@ class GPUCommandProcessor : public DmaVirtDevice
     GPUCommandProcessor(const Params &p);
 
     HSAPacketProcessor& hsaPacketProc();
+    RequestorID vramRequestorId();
 
     void setGPUDevice(AMDGPUDevice *gpu_device);
     void setShader(Shader *shader);