mediaplayer: Fix new[] / delete mismatch

fItems are allocated by new[] at line 31, but deallocated by delete.
Pointed out by Clang Static Analyzer.

Change-Id: I1d8ae0b2214290155612d4b5c6d1ce56676cc892
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3746
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

src/apps/mediaplayer/playlist/MovePLItemsCommand.cpp

@@ -34,7 +34,7 @@ MovePLItemsCommand::MovePLItemsCommand(Playlist* playlist,
 {
 	if (indices.IsEmpty()) {
 		// indicate a bad object state
-		delete fItems;
+		delete[] fItems;
 		fItems = NULL;
 		return;
 	}