[mlir][openacc][NFC] Remove useless OptionalAttr with UnitAttr (llvm#68337)

`UnitAttr` exits or not so adding `OptionalAttr` around it is not
necessary. This patch cleanup this for the `RoutineOp`

Author: clementval

flang/lib/Lower/OpenACC.cpp

@@ -2981,9 +2981,8 @@ genACC(Fortran::lower::AbstractConverter &converter,
   std::stringstream routineOpName;
   routineOpName << accRoutinePrefix.str() << routineCounter++;
   auto routineOp = modBuilder.create<mlir::acc::RoutineOp>(
-      loc, routineOpName.str(), funcName, mlir::StringAttr{}, mlir::UnitAttr{},
-      mlir::UnitAttr{}, mlir::UnitAttr{}, mlir::UnitAttr{}, mlir::UnitAttr{},
-      mlir::UnitAttr{}, mlir::IntegerAttr{});
+      loc, routineOpName.str(), funcName, mlir::StringAttr{}, false, false,
+      false, false, false, false, mlir::IntegerAttr{});
 
   for (const Fortran::parser::AccClause &clause : clauses.v) {
     if (std::get_if<Fortran::parser::AccClause::Seq>(&clause.u)) {

mlir/include/mlir/Dialect/OpenACC/OpenACCOps.td

@@ -1563,12 +1563,12 @@ def OpenACC_RoutineOp : OpenACC_Op<"routine", [IsolatedFromAbove]> {
   let arguments = (ins SymbolNameAttr:$sym_name,
                        SymbolNameAttr:$func_name,
                        OptionalAttr<StrAttr>:$bind_name,
-                       OptionalAttr<UnitAttr>:$gang,
-                       OptionalAttr<UnitAttr>:$worker,
-                       OptionalAttr<UnitAttr>:$vector,
-                       OptionalAttr<UnitAttr>:$seq,
-                       OptionalAttr<UnitAttr>:$nohost,
-                       OptionalAttr<UnitAttr>:$implicit,
+                       UnitAttr:$gang,
+                       UnitAttr:$worker,
+                       UnitAttr:$vector,
+                       UnitAttr:$seq,
+                       UnitAttr:$nohost,
+                       UnitAttr:$implicit,
                        OptionalAttr<APIntAttr>:$gangDim);
 
   let extraClassDeclaration = [{