[MLIR] Adopt LDBG() debug macro in PatternApplicator.cpp (NFC)

Author: joker-eph

mlir/lib/Rewrite/PatternApplicator.cpp

@@ -37,9 +37,9 @@ PatternApplicator::~PatternApplicator() = default;
 #ifndef NDEBUG
 /// Log a message for a pattern that is impossible to match.
 static void logImpossibleToMatch(const Pattern &pattern) {
-  llvm::dbgs() << "Ignoring pattern '" << pattern.getRootKind()
-               << "' because it is impossible to match or cannot lead "
-                  "to legal IR (by cost model)\n";
+  LDBG() << "Ignoring pattern '" << pattern.getRootKind()
+         << "' because it is impossible to match or cannot lead "
+            "to legal IR (by cost model)";
 }
 
 /// Log IR after pattern application.