[riscv64] Remove the Dummy interface descriptor

Port commit 4ae5a813

Change-Id: I2b4fccff6bf5266cd4cf9df45cabe3a19f29ab41
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3609751
Commit-Queue: Yahan Lu <yahan@iscas.ac.cn>
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Reviewed-by: ji qiu <qiuji@iscas.ac.cn>
Commit-Queue: ji qiu <qiuji@iscas.ac.cn>
Cr-Commit-Position: refs/heads/main@{#80205}

src/codegen/riscv64/interface-descriptors-riscv64-inl.h

@@ -231,8 +231,7 @@ constexpr auto ConstructStubDescriptor::registers() {
   // a3: new target
   // a1: target
   // a0: number of arguments
-  // a2: allocation site or undefined
-  return RegisterArray(a1, a3, a0, a2);
+  return RegisterArray(a1, a3, a0);
 }
 
 // static