[riscv64] fix build error

Change-Id: Ifaaa87234ab48869e828ba99e96de0d372538e81
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3647967
Commit-Queue: Yahan Lu <yahan@iscas.ac.cn>
Commit-Queue: ji qiu <qiuji@iscas.ac.cn>
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Reviewed-by: ji qiu <qiuji@iscas.ac.cn>
Cr-Commit-Position: refs/heads/main@{#80536}

src/diagnostics/riscv64/disasm-riscv64.cc

@@ -1631,7 +1631,9 @@ void Decoder::DecodeIType(Instruction* instr) {
       break;
     default:
 #ifdef CAN_USE_RVV_INSTRUCTIONS
-      if (!DecodeRvvVL()) {
+      if (instr->vl_vs_width() != -1) {
+        DecodeRvvVL(instr);
+      } else {
         UNSUPPORTED_RISCV();
       }
       break;
@@ -1667,7 +1669,9 @@ void Decoder::DecodeSType(Instruction* instr) {
       break;
     default:
 #ifdef CAN_USE_RVV_INSTRUCTIONS
-      if (!DecodeRvvVS()) {
+      if (instr->vl_vs_width() != -1) {
+        DecodeRvvVS(instr);
+      } else {
         UNSUPPORTED_RISCV();
       }
       break;