[arm64] Only run FJCVTZS test when the instruction is available

Change-Id: I3d2da18477df775b6ecc8e358a02f4e838961831
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2241522
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68365}

test/cctest/test-assembler-arm64.cc

@@ -11156,10 +11156,13 @@ static void FjcvtzsHelper(uint64_t value, uint64_t expected,
   __ Fjcvtzs(w0, d0);
   __ Mrs(x1, NZCV);
   END();
-  RUN();
 
-  CHECK_EQUAL_64(expected, x0);
-  CHECK_EQUAL_32(expected_z, w1);
+  if (CpuFeatures::IsSupported(JSCVT)) {
+    RUN();
+
+    CHECK_EQUAL_64(expected, x0);
+    CHECK_EQUAL_32(expected_z, w1);
+  }
 }
 
 TEST(fjcvtzs) {