Mark buffer_compress_chunk as child of buffer_compress_percentage

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/options.c b/options.c
index 0680659..463b66d 100644
--- a/options.c
+++ b/options.c
@@ -2025,6 +2025,7 @@
 		.name	= "buffer_compress_chunk",
 		.type	= FIO_OPT_INT,
 		.off1	= td_var_offset(compress_chunk),
+		.parent	= "buffer_compress_percentage",
 		.help	= "Size of compressible region in buffer",
 	},
 	{