[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/CodeGen/PatchableFunction.cpp b/llvm/lib/CodeGen/PatchableFunction.cpp
index ad9166f..00e7297 100644
--- a/llvm/lib/CodeGen/PatchableFunction.cpp
+++ b/llvm/lib/CodeGen/PatchableFunction.cpp
@@ -75,7 +75,7 @@
                  .addImm(FirstActualI->getOpcode());
 
   for (auto &MO : FirstActualI->operands())
-    MIB.addOperand(MO);
+    MIB.add(MO);
 
   FirstActualI->eraseFromParent();
   MF.ensureAlignment(4);