watchdog: Consistently return errors for dbus failures

This adds return codes for all of the dbus failures which inform the
host that it should retry the IPMI command as dbus related errors should
be ephemeral.

Change-Id: I090f488535625a996347677a0c8addbdff0996c0
Signed-off-by: William A. Kennington III <wak@google.com>
2 files changed