bus: follow D-bus policy
Tizen D-bus policy does not support Smack rule.
The following patch set of D-bus probably affects dbus-daemon which is used for
accessibility.
https://review.tizen.org/gerrit/#/c/133270/
It was not possilbe to launch dbus-daemon with following error message.
org.a11y.Bus[2457]: Failed to start message bus:
Attribute "smack" is invalid on <policy> element in this context
org.a11y.Bus[2457]: Failed to launch bus: Bus exited with code 1
Change-Id: I67435b1a27f91193348d1e699805b6d09be8fddc