PPC/s390: [cleanup] Remove operator-> implementations from Object subclasses

Port 3c6ecf71

Original Commit Message:

    Object::operator-> was removed in
    https://chromium-review.googlesource.com/c/v8/v8/+/1624788 but a few
    subclasses still had their own implementations.

R=seth.brenith@microsoft.com, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I0f4902250ef1f80d2e06c71f27a0bee0717cf5ec
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1888191Reviewed-by: Milad Farazmand <miladfar@ca.ibm.com>
Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#64623}

src/builtins/s390/builtins-s390.cc

@@ -1422,7 +1422,7 @@ static void Generate_InterpreterEnterBytecode(MacroAssembler* masm) {
   __ LoadP(r4, MemOperand(r4));
 
   __ bind(&trampoline_loaded);
-  __ AddP(r14, r4, Operand(interpreter_entry_return_pc_offset->value()));
+  __ AddP(r14, r4, Operand(interpreter_entry_return_pc_offset.value()));
 
   // Initialize the dispatch table register.
   __ Move(