[CodeGen] Rename MachineInstrBuilder::addOperand. NFC

Rename from addOperand to just add, to match the other method that has been
added to MachineInstrBuilder for adding more than just 1 operand.

See https://reviews.llvm.org/D28057 for the whole discussion.

Differential Revision: https://reviews.llvm.org/D28556

llvm-svn: 291891
diff --git a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
index dd31dc6..c5f1217 100644
--- a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -497,24 +497,24 @@
       int Op32DstIdx = AMDGPU::getNamedOperandIdx(Op32, AMDGPU::OpName::vdst);
       if (Op32DstIdx != -1) {
         // dst
-        Inst32.addOperand(MI.getOperand(0));
+        Inst32.add(MI.getOperand(0));
       } else {
         assert(MI.getOperand(0).getReg() == AMDGPU::VCC &&
                "Unexpected case");
       }
 
 
-      Inst32.addOperand(*TII->getNamedOperand(MI, AMDGPU::OpName::src0));
+      Inst32.add(*TII->getNamedOperand(MI, AMDGPU::OpName::src0));
 
       const MachineOperand *Src1 =
           TII->getNamedOperand(MI, AMDGPU::OpName::src1);
       if (Src1)
-        Inst32.addOperand(*Src1);
+        Inst32.add(*Src1);
 
       if (Src2) {
         int Op32Src2Idx = AMDGPU::getNamedOperandIdx(Op32, AMDGPU::OpName::src2);
         if (Op32Src2Idx != -1) {
-          Inst32.addOperand(*Src2);
+          Inst32.add(*Src2);
         } else {
           // In the case of V_CNDMASK_B32_e32, the explicit operand src2 is
           // replaced with an implicit read of vcc. This was already added