[wasm-simd] Fix typo in ext mul interpreter implementation

There is a typo getting the values of the lanes, only on big-endian
systems. (On little-endian systems, the use of LANE macro hides the
error).

Bug: v8:11008
Change-Id: I99efde506dab443efd336346ec920fcd957daae2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2486614Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70666}

test/common/wasm/wasm-interpreter.cc

@@ -2873,8 +2873,8 @@ class WasmInterpreterInternals {
     for (size_t dst = 0; start < end; ++start, ++dst) {
       // Need static_cast for unsigned narrow types.
       res.val[LANE(dst, res)] =
-          MultiplyLong<wide>(static_cast<narrow>(s1.val[LANE(start, s)]),
-                             static_cast<narrow>(s2.val[LANE(start, s)]));
+          MultiplyLong<wide>(static_cast<narrow>(s1.val[LANE(start, s1)]),
+                             static_cast<narrow>(s2.val[LANE(start, s2)]));
     }
     Push(WasmValue(Simd128(res)));
     return true;