Revert of [turbofan] Add alignment parameter to StackSlot operator

src/compiler/s390/instruction-selector-s390.cc

Index: src/compiler/s390/instruction-selector-s390.cc
diff --git a/src/compiler/s390/instruction-selector-s390.cc b/src/compiler/s390/instruction-selector-s390.cc
index f4e8ea13d2be5c62ed78393fe3a4c9acb87eca5a..3ff3f2354cc6af0494a624933b31d5b00d01ddc9 100644
--- a/src/compiler/s390/instruction-selector-s390.cc
+++ b/src/compiler/s390/instruction-selector-s390.cc
@@ -701,15 +701,6 @@
 }
 
 }  // namespace
-
-void InstructionSelector::VisitStackSlot(Node* node) {
-  StackSlotRepresentation rep = StackSlotRepresentationOf(node->op());
-  int slot = frame_->AllocateSpillSlot(rep.size());
-  OperandGenerator g(this);
-
-  Emit(kArchStackSlot, g.DefineAsRegister(node),
-       sequence()->AddImmediate(Constant(slot)), 0, nullptr);
-}
 
 void InstructionSelector::VisitLoad(Node* node) {
   S390OperandGenerator g(this);