USB: Nikon D40X unusual_devs entry

Not surprisingly the Nikon D40X DSC needs the same quirks as the D40,
but it has a separate ID.
See http://bugs.gentoo.org/show_bug.cgi?id=191431

From: Ortwin Glück <odi@odi.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>