[AMDGPU] Make AMDGPULowerKernelArguments a module pass

After c4d8920 AMDGPULowerKernelArguments may clone functions and
modify the kernel signature of those functions to enable preloading
hidden kernel arguments. These leftover functions end up as dead
declarations which may cause issues with the toolchain downstream.

This patch makes AMDGPULowerKernelArguments a module pass so that we can
safely erase these leftover declarations.

There is also some small refactoring to avoid duplicated logic with the
different pass managers. The update changes the pass interfaces to look
similar to other AMDGPU passes that have been migrated over to the new
pass manager.

Author: kerbowa

llvm/lib/Target/AMDGPU/AMDGPU.h

@@ -111,9 +111,9 @@ ModulePass *createAMDGPUCtorDtorLoweringLegacyPass();
 void initializeAMDGPUCtorDtorLoweringLegacyPass(PassRegistry &);
 extern char &AMDGPUCtorDtorLoweringLegacyPassID;
 
-FunctionPass *createAMDGPULowerKernelArgumentsPass();
-void initializeAMDGPULowerKernelArgumentsPass(PassRegistry &);
-extern char &AMDGPULowerKernelArgumentsID;
+ModulePass *createAMDGPULowerKernelArgumentsLegacyPass(const TargetMachine *TM);
+void initializeAMDGPULowerKernelArgumentsLegacyPass(PassRegistry &);
+extern char &AMDGPULowerKernelArgumentsLegacyPassID;
 
 FunctionPass *createAMDGPUPromoteKernelArgumentsPass();
 void initializeAMDGPUPromoteKernelArgumentsPass(PassRegistry &);
@@ -310,7 +310,7 @@ class AMDGPULowerKernelArgumentsPass
 
 public:
   AMDGPULowerKernelArgumentsPass(TargetMachine &TM) : TM(TM){};
-  PreservedAnalyses run(Function &, FunctionAnalysisManager &);
+  PreservedAnalyses run(Module &, ModuleAnalysisManager &);
 };
 
 struct AMDGPUAttributorOptions {