[maglev] Missing ReduceResult::Fail()

Missing nullptr -> ReduceResult::Fail in refactor:
https://chromium-review.googlesource.com/c/v8/v8/+/4218731

Fixed: chromium:1413052
Bug: v8:7700
Change-Id: I93d24916b20d42a650545a11c81a369d53bd5764
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4224031
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85663}

src/maglev/maglev-graph-builder.cc

@@ -3161,7 +3161,7 @@ ReduceResult MaglevGraphBuilder::TryBuildLoadDataView(const CallArguments& args,
                                                       ExternalArrayType type) {
   if (!broker()->dependencies()->DependOnArrayBufferDetachingProtector()) {
     // TODO(victorgomes): Add checks whether the array has been detached.
-    return nullptr;
+    return ReduceResult::Fail();
   }
   // TODO(victorgomes): Add data view to known types.
   ValueNode* receiver = GetTaggedOrUndefined(args.receiver());