[LoongArch] Fix a typo in LoongArchCCAssignFn. NFC (#116178)

Author: zhaoqi5

llvm/lib/Target/LoongArch/LoongArchISelLowering.h

@@ -284,7 +284,7 @@ class LoongArchTargetLowering : public TargetLowering {
                                    unsigned ValNo, MVT ValVT,
                                    CCValAssign::LocInfo LocInfo,
                                    ISD::ArgFlagsTy ArgFlags, CCState &State,
-                                   bool IsFixed, bool IsReg, Type *OrigTy);
+                                   bool IsFixed, bool IsRet, Type *OrigTy);
 
   void analyzeInputArgs(MachineFunction &MF, CCState &CCInfo,
                         const SmallVectorImpl<ISD::InputArg> &Ins, bool IsRet,