coding-style: fix mismatch of jump label name

Commit 865a1caa ("CodingStyle: Clarify and complete chapter 7")
renamed the label "out_buffer" to "out_free_buffer", but missed to
change this line.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>