Use OpState::operator->() to get to member functions in Operation so we can remove the corresponding methods from OpState.

PiperOrigin-RevId: 346723312
diff --git a/experimental/ModelBuilder/ModelBuilder.cpp b/experimental/ModelBuilder/ModelBuilder.cpp
index aff020f..7e567d3 100644
--- a/experimental/ModelBuilder/ModelBuilder.cpp
+++ b/experimental/ModelBuilder/ModelBuilder.cpp
@@ -245,7 +245,7 @@
       SymbolTable::lookupNearestSymbolFrom<FuncOp>(callerFunc, functionName);
   if (!calleeFunc) {
     OpBuilder::InsertionGuard insertGuard(builder);
-    auto module = callerFunc.getParentOfType<ModuleOp>();
+    auto module = callerFunc->getParentOfType<ModuleOp>();
     builder.setInsertionPointToStart(module.getBody());
     calleeFunc = builder.create<FuncOp>(
         module.getLoc(), functionName,