Define bus used by mapper in settings_manager.py
Define bus used by mapper in settings_manager.py

Undefined bus in mapper = obmc.mapper.Mapper(bus) in
settings_manager.py causes a failure. This patch defines
the bus.

Resolves openbmc/openbmc#806

Change-Id: I1989c1246c34f8be98591f439bfa1847f3325e00
Signed-off-by: Sergey Solomin <bad8d7ca4c6095b3375ad0bfef82851c16e1f680@us.ibm.com>

openbmc/phosphor-settingsd,openbmc/phosphor-settingsd,openbmc/phosphor-settingsd