[X86] Fix -Wsign-compare in X86MCInstLower.cpp (NFC)

llvm-project/llvm/lib/Target/X86/X86MCInstLower.cpp:1867:20:
 error: comparison of integers of different signs: 'int' and 'unsigned int' [-Werror,-Wsign-compare]
      if (SclWidth == C->getType()->getScalarSizeInBits()) {
          ~~~~~~~~ ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

Author: DamonFool

llvm/lib/Target/X86/X86MCInstLower.cpp

@@ -1864,7 +1864,7 @@ static void addConstantComments(const MachineInstr *MI,
 
     if (auto *C =
             X86::getConstantFromPool(*MI, MI->getOperand(1 + X86::AddrDisp))) {
-      if (SclWidth == C->getType()->getScalarSizeInBits()) {
+      if ((unsigned)SclWidth == C->getType()->getScalarSizeInBits()) {
         if (auto *CI = dyn_cast<ConstantInt>(C)) {
           CS << "[";
           printConstant(CI->getValue(), CS);