[riscv64] Fix a Int64Mul error in instruction selection.

Port 9a900169

The second parameter of Int64Mul may be a 64-bit immediate value,
treating it as a 32-bit value will lose the upper 32 bits.

Bug: v8:12373

Change-Id: Ib824db839219307ba390a6dc3c697bedb792046f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3275135
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Commit-Queue: ji qiu <qiuji@iscas.ac.cn>
Reviewed-by: ji qiu <qiuji@iscas.ac.cn>
Cr-Commit-Position: refs/heads/main@{#77862}

src/compiler/backend/riscv64/instruction-selector-riscv64.cc

@@ -941,7 +941,7 @@ void InstructionSelector::VisitInt64Mul(Node* node) {
   Int64BinopMatcher m(node);
   // TODO(dusmil): Add optimization for shifts larger than 32.
   if (m.right().HasResolvedValue() && m.right().ResolvedValue() > 0) {
-    uint32_t value = static_cast<uint32_t>(m.right().ResolvedValue());
+    uint64_t value = static_cast<uint64_t>(m.right().ResolvedValue());
     if (base::bits::IsPowerOfTwo(value)) {
       Emit(kRiscvShl64 | AddressingModeField::encode(kMode_None),
            g.DefineAsRegister(node), g.UseRegister(m.left().node()),