[AMDGPU][AsmParser][NFC] Remove an unused function.

Was added in <https://reviews.llvm.org/D63293>, but never used.

Reviewed By: foad

Differential Revision: https://reviews.llvm.org/D154331

Author: kosarev

llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp

@@ -962,10 +962,6 @@ class AMDGPUOperand : public MCParsedAsmOperand {
 
   void addRegOperands(MCInst &Inst, unsigned N) const;
 
-  void addBoolRegOperands(MCInst &Inst, unsigned N) const {
-    addRegOperands(Inst, N);
-  }
-
   void addRegOrImmOperands(MCInst &Inst, unsigned N) const {
     if (isRegKind())
       addRegOperands(Inst, N);