[fir][NFC] Add disclaimer to affine promotion/demotion passes

[clementval]

Summary

AffinePromotion and AffineDemotion passes where upstreamed
in their current status from fir-dev. In order to make sure everybody
is on the same page, this patch add some comments to state that.

flang/lib/Optimizer/Transforms/AffineDemotion.cpp

 //===-- AffineDemotion.cpp -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+//
+// This transformation is a prototype that demote affine dialects operations
+// after optimizations to FIR loops operations.
+// It is used after the AffinePromotion pass.
+// It is not part of the production pipeline and would need more work in order
+// to be used in production.
+// More information can be found in this presentation:
+// https://slides.com/rajanwalia/deck
+//
+//===----------------------------------------------------------------------===//
 
 #include "PassDetail.h"
 #include "flang/Optimizer/Dialect/FIRDialect.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
 #include "flang/Optimizer/Dialect/FIRType.h"
 #include "flang/Optimizer/Transforms/Passes.h"
 #include "mlir/Conversion/AffineToStandard/AffineToStandard.h"
 #include "mlir/Dialect/Affine/IR/AffineOps.h"

flang/lib/Optimizer/Transforms/AffinePromotion.cpp

 //===-- AffinePromotion.cpp -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+//
+// This transformation is a prototype that promote FIR loops operations
+// to affine dialect operations.
+// It is not part of the production pipeline and would need more work in order
+// to be used in production.
+// More information can be found in this presentation:
+// https://slides.com/rajanwalia/deck
+//
+//===----------------------------------------------------------------------===//
 
 #include "PassDetail.h"
 #include "flang/Optimizer/Dialect/FIRDialect.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
 #include "flang/Optimizer/Dialect/FIRType.h"
 #include "flang/Optimizer/Transforms/Passes.h"
 #include "mlir/Dialect/Affine/IR/AffineOps.h"
 #include "mlir/Dialect/SCF/SCF.h"

 
 using namespace fir;
 
 namespace {
 struct AffineLoopAnalysis;
 struct AffineIfAnalysis;
 
 /// Stores analysis objects for all loops and if operations inside a function
-///  these analysis are used twice, first for marking operations for rewrite and
-///  second when doing rewrite.
+/// these analysis are used twice, first for marking operations for rewrite and
+/// second when doing rewrite.
 struct AffineFunctionAnalysis {
   explicit AffineFunctionAnalysis(mlir::FuncOp funcOp) {
     for (fir::DoLoopOp op : funcOp.getOps<fir::DoLoopOp>())
       loopAnalysisMap.try_emplace(op, op, *this);
   }
 
   AffineLoopAnalysis getChildLoopAnalysis(fir::DoLoopOp op) const;