Restore settings to default on error
Restore settings to default on error

In the event that the value read from a persistence file is
invalid, currently a ValueError exception is thrown and the
settingsd fails to run.  Instead, catch this condition and
restore the setting to default.

Fixes openbmc/openbmc#1442.

Change-Id: I22ce8837d9c48b21bab050f1de9b730ec219bc4b
Signed-off-by: Patrick Williams <cbb7353e6d953ef360baf960c122346276c6e320@stwcx.xyz>

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