[riscv64] Fix emit_u32_to_uintptr to be zero-extended

Change-Id: I95a5768af19174275e2828136ce3ff772886e84f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3585499Reviewed-by: ji qiu <qiuji@iscas.ac.cn>
Commit-Queue: Yahan Lu <yahan@iscas.ac.cn>
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Cr-Commit-Position: refs/heads/main@{#79979}

src/wasm/baseline/riscv64/liftoff-assembler-riscv64.h

@@ -1351,7 +1351,7 @@ void LiftoffAssembler::emit_i64_addi(LiftoffRegister dst, LiftoffRegister lhs,
   TurboAssembler::Add64(dst.gp(), lhs.gp(), Operand(imm));
 }
 void LiftoffAssembler::emit_u32_to_uintptr(Register dst, Register src) {
-  addw(dst, src, zero_reg);
+  ZeroExtendWord(dst, src);
 }
 
 void LiftoffAssembler::emit_f32_neg(DoubleRegister dst, DoubleRegister src) {