[csa][cleanup] TNodify LoadMap

This used to break x64 no embed bot due to it being Large code objects
but no embed no longer exists so this isn't a problem anymore.

Bug: v8:9708, v8:6949, v8:9637
Change-Id: I83836a94ff1747841315d46ca0e7ec5c73bbaf0d
Fix: v8:9637
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2387962Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69692}

src/codegen/code-stub-assembler.cc

@@ -1432,10 +1432,7 @@ TNode<Map> CodeStubAssembler::GetInstanceTypeMap(InstanceType instance_type) {
 }
 
 TNode<Map> CodeStubAssembler::LoadMap(SloppyTNode<HeapObject> object) {
-  // TODO(v8:9637): Do a proper LoadObjectField<Map> and remove UncheckedCast
-  // when we can avoid making Large code objects due to TNodification.
-  return UncheckedCast<Map>(LoadObjectField(object, HeapObject::kMapOffset,
-                                            MachineType::TaggedPointer()));
+  return LoadObjectField<Map>(object, HeapObject::kMapOffset);
 }
 
 TNode<Uint16T> CodeStubAssembler::LoadInstanceType(