how to setup hwsim dbus_xxx test environment

[Li Zhijian]

Hi guys

lkp-tests(https://github.com/fengguang/lkp-tests) enabled hwsim test recently, and currently
we have made most case pass.

but when we test dbus_xx cases, they all failed at prepare_dbus() stage, the error message like this

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root at snb-black /lkp/benchmarks/hwsim/tests/hwsim# ./start.sh ; ./run-tests.py dbus_ap ; ./stop.sh
DEV: wlan0: 02:00:00:00:00:00
DEV: wlan1: 02:00:00:00:01:00
DEV: wlan2: 02:00:00:00:02:00
APDEV: wlan3
APDEV: wlan4
START dbus_ap 1/1
Test: D-Bus AddNetwork for AP mode
Skip test case: Could not connect to D-Bus: fi.w1.wpa_supplicant1.InterfaceUnknown: wpa_supplicant knows nothing about this interface.
SKIP dbus_ap 0.043872 2017-06-02 16:39:13.946549
passed all 0 test case(s)
skipped 1 test case(s)
--------------------------
it seems that something wrong at my environment.

any ideas ?

Thanks