Enable sim support in ivi

capi-telephony-sim package will talk to Samsung telephony stack which we don't
have in IVI. Currently, it uses ofono as the telephony stack. So, in client, we
have to use g_dbus* API to get corresponding sim attribute.

BUG=XWALK-2039
i do not see why not assign msin_ directly as return value of g_variant_get_string