update debian/copyright for backported include/linux/firewire-cdev.h

Hi Hayashi-san,

I apologize to have forgot mentioning about the backported header from Linux kernel in libhinawa v2.6.0 release... Would I ask you to check the patch below and apply it to your next work for packaging? (maybe -2).

From 7f3b67214284f9c5f8fee442670b616f2dc49acf Mon Sep 17 00:00:00 2001
From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Thu, 3 Aug 2023 18:27:18 +0900
Subject: [PATCH] debian: note about linux/firewire-cdev.h

A commit 3600f84fdc95 ("backport UAPI of Linux FireWire subsystem from
Linux kernel v6.5 prepatch") imports the part of source of Linux kernel
for UAPI of FireWire subsystem.

This commit updates debian/copyright to describe the file.
---
 debian/copyright | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/debian/copyright b/debian/copyright
index 6f4c523..a60d599 100644
--- a/debian/copyright
+++ b/debian/copyright
@@ -18,6 +18,10 @@ Files: include/sound/firewire.h
 Copyright: 1991-2012 Linus Torvalds and many others
 License: GPL-2
 
+Files: include/linux/firewire-cdev.h
+Copyright: 1991-2023 Linus Torvalds and many others
+License: GPL-2
+
 License: GPL-2
  On Debian systems, the complete text of the GNU General Public License version
  2 can be found in `/usr/share/common-licenses/GPL-2'.
-- 
2.39.2