[SelectionDAG] Remove unnecessary cast of nullptr in std::fill call. NFC

Author: topperc

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -1418,10 +1418,8 @@ void SelectionDAG::clear() {
   TargetExternalSymbols.clear();
   MCSymbols.clear();
   SDEI.clear();
-  std::fill(CondCodeNodes.begin(), CondCodeNodes.end(),
-            static_cast<CondCodeSDNode*>(nullptr));
-  std::fill(ValueTypeNodes.begin(), ValueTypeNodes.end(),
-            static_cast<SDNode*>(nullptr));
+  std::fill(CondCodeNodes.begin(), CondCodeNodes.end(), nullptr);
+  std::fill(ValueTypeNodes.begin(), ValueTypeNodes.end(), nullptr);
 
   EntryNode.UseList = nullptr;
   InsertNode(&EntryNode);