[SelectionDAG] Remove isNullValue and isAllOnesValue

These functions have been deprecated since:

  commit f271e5d
  Author: Kazu Hirata <kazu@google.com>
  Date:   Sun Mar 12 18:25:07 2023 -0700

Differential Revision: https://reviews.llvm.org/D153317

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

@@ -1615,11 +1615,7 @@ class ConstantSDNode : public SDNode {
 
   bool isOne() const { return Value->isOne(); }
   bool isZero() const { return Value->isZero(); }
-  LLVM_DEPRECATED("use isZero instead", "isZero")
-  bool isNullValue() const { return isZero(); }
   bool isAllOnes() const { return Value->isMinusOne(); }
-  LLVM_DEPRECATED("use isAllOnes instead", "isAllOnes")
-  bool isAllOnesValue() const { return isAllOnes(); }
   bool isMaxSignedValue() const { return Value->isMaxValue(true); }
   bool isMinSignedValue() const { return Value->isMinValue(true); }