[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/Mips/MipsInstrInfo.cpp b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
index 19af191..86bf103 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
@@ -482,7 +482,7 @@
       MIB->RemoveOperand(0);
 
     for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
-      MIB.addOperand(I->getOperand(J));
+      MIB.add(I->getOperand(J));
     }
 
     MIB.addImm(0);
@@ -492,7 +492,7 @@
       if (BranchWithZeroOperand && (unsigned)ZeroOperandPosition == J)
         continue;
 
-      MIB.addOperand(I->getOperand(J));
+      MIB.add(I->getOperand(J));
     }
   }