[PATCH] USB: another cdc descriptor

This adds another CDC descriptor type to <linux/usb_cdc.h>; the main claim
to fame for this is that some Motorola phones include it.  It's not currently
needed by any driver code; included for completeness.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>