[riscv64] Delete extra scratch reg

Change-Id: Ib145fcc89ff15d06de8205e67280798ed8f36aac
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3612667Reviewed-by: ji qiu <qiuji@iscas.ac.cn>
Commit-Queue: ji qiu <qiuji@iscas.ac.cn>
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Cr-Commit-Position: refs/heads/main@{#80242}

src/builtins/riscv64/builtins-riscv64.cc

@@ -192,8 +192,6 @@ void Builtins::Generate_JSConstructStubGeneric(MacroAssembler* masm) {
         static_cast<uint32_t>(FunctionKind::kDefaultDerivedConstructor),
         static_cast<uint32_t>(FunctionKind::kDerivedConstructor),
         &not_create_implicit_receiver);
-    Register scratch = func_info;
-    Register scratch2 = temps.Acquire();
     // If not derived class constructor: Allocate the new receiver object.
     __ Call(BUILTIN_CODE(masm->isolate(), FastNewObject),
             RelocInfo::CODE_TARGET);