Wait until  uci for wireless is available

Even though mac80211_hwsim is loaded, wireless setting sometimes
doesn't work.
So use uci show command instead to check if wireless setting is
available.

Bug: 191348818
Test: repeat launch_cvd and check wifi status
Change-Id: Ice0a176b19c21201e05e68f9ec65451bc93f90e6
1 file changed