Documentation/printf: Use literal fwnode_handle

Documentation/printf: Use literal fwnode_handle

When looking for fwnode_handle in the printk format documentation, it is
only found in the Chinese translation:

    $ git grep fwnode_handle -- Documentation/*printk-formats.rst
    Documentation/translations/zh_CN/core-api/printk-formats.rst:用于打印fwnode_handles的消息。默认情况下是打印完整的节点名称，包括路径。

This happens because the original documentation talks about "fwnode
handles", without mentioning the actual type name.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Kunwu Chan <kunwu.chan@linux.dev>
Reviewed-by: Kunwu Chan <kunwu.chan@linux.dev>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Fixes: 3bd32d6a2ee62db3 ("lib/vsprintf: Add %pfw conversion specifier for printing fwnode names")
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/07262c55e82fc4a3e3dbe7c45713b14955271e7f.1754552156.git.geert+renesas@glider.be