[GlobalIsel][X86] Remove unused private field 'TM' in X86LegalizerInfo (NFC)

/data/llvm-project/llvm/lib/Target/X86/X86LegalizerInfo.h:30:27: error: private field 'TM' is not used [-Werror,-Wunused-private-field]
  const X86TargetMachine &TM;
                          ^
1 error generated.

Author: DamonFool

llvm/lib/Target/X86/X86LegalizerInfo.cpp

@@ -26,7 +26,7 @@ using namespace LegalityPredicates;
 
 X86LegalizerInfo::X86LegalizerInfo(const X86Subtarget &STI,
                                    const X86TargetMachine &TM)
-    : Subtarget(STI), TM(TM) {
+    : Subtarget(STI) {
 
   bool Is64Bit = Subtarget.is64Bit();
   bool HasSSE1 = Subtarget.hasSSE1();

llvm/lib/Target/X86/X86LegalizerInfo.h

@@ -27,7 +27,6 @@ class X86LegalizerInfo : public LegalizerInfo {
   /// Keep a reference to the X86Subtarget around so that we can
   /// make the right decision when generating code for different targets.
   const X86Subtarget &Subtarget;
-  const X86TargetMachine &TM;
 
 public:
   X86LegalizerInfo(const X86Subtarget &STI, const X86TargetMachine &TM);