[NFC][AMDGPU] Remove the empty FPM as well as the adaptor to MPM (#114558)

Author: shiltian

llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

@@ -740,8 +740,6 @@ void AMDGPUTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
 
   PB.registerPipelineStartEPCallback(
       [](ModulePassManager &PM, OptimizationLevel Level) {
-        FunctionPassManager FPM;
-        PM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
         if (EnableHipStdPar)
           PM.addPass(HipStdParAcceleratorCodeSelectionPass());
       });