Fix comments.

Change-Id: Ife256a2523b6513bfb5e051a099583db2060b3ba
diff --git a/src/fdt_test.cc b/src/fdt_test.cc
index cb0d14c..6d55242 100644
--- a/src/fdt_test.cc
+++ b/src/fdt_test.cc
@@ -29,7 +29,7 @@
  * };
  *
  * $ dtc --boot-cpu 0 --in-format dts --out-format dtb --out-version 17 test.dts
- * | xxd
+ * | xxd -i
  */
 
 static const uint8_t test_dtb[] = {