[mlir] [NFC] Add a newline to debug message at inserting of InterfaceMap

At inserting of InterfaceMap, a debug message lacked a newline, so it repeatedly displayed this message within a single line.
Clean up the debug log by inserting a newline at the end of the message.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D150182

mlir/lib/Support/InterfaceSupport.cpp

@@ -25,7 +25,7 @@ void detail::InterfaceMap::insert(TypeID interfaceId, void *conceptImpl) {
         return compare(it.first, id);
       });
   if (it != interfaces.end() && it->first == interfaceId) {
-    LLVM_DEBUG(llvm::dbgs() << "Ignoring repeated interface registration");
+    LLVM_DEBUG(llvm::dbgs() << "Ignoring repeated interface registration\n");
     free(conceptImpl);
     return;
   }