[AArch64][ISel] Remove unused variable 'TRI' (NFC)

/Users/jiefu/llvm-project/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp:6629:32: error: unused variable 'TRI' [-Werror,-Wunused-variable]
    const AArch64RegisterInfo *TRI = Subtarget->getRegisterInfo();
                               ^
1 error generated.

Author: DamonFool

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -6626,7 +6626,6 @@ SDValue AArch64TargetLowering::LowerFormalArguments(
   // Insert the SMSTART if this is a locally streaming function and
   // make sure it is Glued to the last CopyFromReg value.
   if (IsLocallyStreaming) {
-    const AArch64RegisterInfo *TRI = Subtarget->getRegisterInfo();
     Chain =
         changeStreamingMode(DAG, DL, /*Enable*/ true, DAG.getRoot(), Glue,
                             DAG.getConstant(0, DL, MVT::i64), /*Entry*/ true);