charts: add full MO and MT voice call diagram

Add voice_call_full.msc, generated from a real 2G<->3G voice call log fed to
msc_log_to_ladder.py.

The idea is to document how the voice call sequence of events changes in
upcoming patches.

Change-Id: I8a907d6a4ece1f3ad78da75a8c3e3e76afd5418d
2 files changed