[PowerPC] [NFC] Refine PowerPC GISel files according to clang-tidy checks (#129780)

Code cleanup for PowerPC GISel files such as renaming header guards and
removing unused includes.

Author: MarcusBoay

llvm/lib/Target/PowerPC/GISel/PPCCallLowering.h

@@ -16,7 +16,6 @@
 
 #include "PPCISelLowering.h"
 #include "llvm/CodeGen/GlobalISel/CallLowering.h"
-#include "llvm/IR/CallingConv.h"
 
 namespace llvm {
 

llvm/lib/Target/PowerPC/GISel/PPCLegalizerInfo.h

@@ -9,8 +9,8 @@
 /// This file declares the targeting of the Machinelegalizer class for PowerPC
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIB_TARGET_POWERPC_GISEL_PPCMACHINELEGALIZER_H
-#define LLVM_LIB_TARGET_POWERPC_GISEL_PPCMACHINELEGALIZER_H
+#ifndef LLVM_LIB_TARGET_POWERPC_GISEL_PPCLEGALIZERINFO_H
+#define LLVM_LIB_TARGET_POWERPC_GISEL_PPCLEGALIZERINFO_H
 
 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
 

llvm/lib/Target/PowerPC/GISel/PPCRegisterBankInfo.h

@@ -11,8 +11,8 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIB_TARGET_PPC_GISEL_PPCREGISTERBANKINFO_H
-#define LLVM_LIB_TARGET_PPC_GISEL_PPCREGISTERBANKINFO_H
+#ifndef LLVM_LIB_TARGET_POWERPC_GISEL_PPCREGISTERBANKINFO_H
+#define LLVM_LIB_TARGET_POWERPC_GISEL_PPCREGISTERBANKINFO_H
 
 #include "llvm/CodeGen/RegisterBank.h"
 #include "llvm/CodeGen/RegisterBankInfo.h"