[RISCV] Remove now unused immzero operand type. NFC

Author: topperc

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.h

@@ -330,7 +330,6 @@ enum OperandType : unsigned {
   OPERAND_UIMM32,
   OPERAND_UIMM48,
   OPERAND_UIMM64,
-  OPERAND_ZERO,
   OPERAND_THREE,
   OPERAND_FOUR,
   OPERAND_SIMM5,

llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

@@ -2859,9 +2859,6 @@ bool RISCVInstrInfo::verifyInstruction(const MachineInstr &MI,
         case RISCVOp::OPERAND_UIMM16_NONZERO:
           Ok = isUInt<16>(Imm) && (Imm != 0);
           break;
-        case RISCVOp::OPERAND_ZERO:
-          Ok = Imm == 0;
-          break;
         case RISCVOp::OPERAND_THREE:
           Ok = Imm == 3;
           break;

llvm/lib/Target/RISCV/RISCVInstrInfoC.td

@@ -57,12 +57,6 @@ def simm6nonzero : RISCVOp,
   }];
 }
 
-def immzero : RISCVOp,
-              ImmLeaf<XLenVT, [{return (Imm == 0);}]> {
-  let ParserMatchClass = ImmZeroAsmOperand;
-  let OperandType = "OPERAND_ZERO";
-}
-
 def CLUIImmAsmOperand : AsmOperandClass {
   let Name = "CLUIImm";
   let RenderMethod = "addImmOperands";