Telephony: add support for additional information

As per ETSI 102 223 section 8.12, for some general results, it is
mandatory for the terminal to provide a specific cause value as
additional information.

This patch adds this support to the framework.

Change-Id: Ie22e60412d674e24f9ebf13d02da4b39cb2dd253
Author: Guillaume Lucas <guillaume.lucas@intel.com>
Signed-off-by: Guillaume Lucas <guillaume.lucas@intel.com>
Signed-off-by: Arun Ravindran <arun.ravindran@intel.com>
Signed-off-by: Jeevaka Badrappan <jeevaka.badrappan@intel.com>
Signed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 29915