The dn->name is expected to be used as a literal, so add the missing
"%s".

Fixes: 263b4c1a (ACPI / property: Expose data-only subnodes via sysfs)
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>