[Atomics] Remove Atomics code stubs; use TF ops

src/s390/interface-descriptors-s390.cc

Index: src/s390/interface-descriptors-s390.cc
diff --git a/src/s390/interface-descriptors-s390.cc b/src/s390/interface-descriptors-s390.cc
index 9f24f5761be45c74c1535879592e8e9e5a11ec50..9edc4ff0e62cb1edff8cc3f905c92716a6fc7187 100644
--- a/src/s390/interface-descriptors-s390.cc
+++ b/src/s390/interface-descriptors-s390.cc
@@ -377,14 +377,6 @@ void ResumeGeneratorDescriptor::InitializePlatformSpecific(
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
-void AtomicsLoadDescriptor::InitializePlatformSpecific(
-    CallInterfaceDescriptorData* data) {
-  Register registers[] = {
-      r3,  // the typedarray object
-      r2   // the index to load (untagged)
-  };
-  data->InitializePlatformSpecific(arraysize(registers), registers);
-}
 }  // namespace internal
 }  // namespace v8