[wasm-simd] Fix endianness issue on AddExtAddPairwise tests

ReadLittleEndianValue needs to be used to make sure
value is returned correctly on BE machines.

Change-Id: I02a64cded4f5dcccd39f1109c4179bebf9231a70
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2941038Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74954}

test/cctest/wasm/test-run-wasm-simd.cc

@@ -3357,7 +3357,7 @@ void RunAddExtAddPairwiseTest(
   r.Call();
 
   for (size_t i = 0; i < expectedOutput.size(); i++) {
-    CHECK_EQ(expectedOutput[i], x[i]);
+    CHECK_EQ(expectedOutput[i], ReadLittleEndianValue<T>(&x[i]));
   }
 }