[Polly] Mention correct flag in debug output. NFCI.

GitOrigin-RevId: c6913905d198bf1da34cd717742cec62ea9c3b72
diff --git a/lib/Analysis/ScopDetection.cpp b/lib/Analysis/ScopDetection.cpp
index 51d8ddd..65b5228 100644
--- a/lib/Analysis/ScopDetection.cpp
+++ b/lib/Analysis/ScopDetection.cpp
@@ -1751,7 +1751,7 @@
   if (!OnlyRegion.empty() &&
       !CurRegion.getEntry()->getName().count(OnlyRegion)) {
     LLVM_DEBUG({
-      dbgs() << "Region entry does not match -polly-region-only";
+      dbgs() << "Region entry does not match -polly-only-region";
       dbgs() << "\n";
     });
     return false;