[ARM64] [turbofan] Use 'mvn' rather than an equivalent 'orn'.

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index b32a53b9cb09931405d5e7e0fa5008da8170ca38..775f519519a0df93089cc1da5c17f7dbcf14e8ae 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -558,12 +558,11 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
               i.InputRegister32(0));
       break;
     }
-    // TODO(dcarney): use mvn instr??
     case kArm64Not:
-      __ Orn(i.OutputRegister(), xzr, i.InputOperand(0));
+      __ Mvn(i.OutputRegister(), i.InputOperand(0));
       break;
     case kArm64Not32:
-      __ Orn(i.OutputRegister32(), wzr, i.InputOperand32(0));
+      __ Mvn(i.OutputRegister32(), i.InputOperand32(0));
       break;
     case kArm64Neg:
       __ Neg(i.OutputRegister(), i.InputOperand(0));