* Try to make sure restoreWifiAsync eventually sends a NetworkConnected
event...
re: #5109
* Take a page from @shermp's book, and make sure wpa_supplicant managed to
connect to the AP before acquiring an IP.
Tear down WiFi modules in case of failure.
c.f., https://github.com/shermp/Kobo-UNCaGED/pull/21
* Don't let restore-wifi-async.sh enable WiFi behind our back when we're
killing it to start Nickel...
* Don't even call ping if there's no default gw
# Make sure we kill the WiFi first, because nickel apparently doesn't like it if it's up... (cf. #1520)
# NOTE: That check is possibly wrong on PLATFORM == freescale (because I don't know if the sdio_wifi_pwr module exists there), but we don't terribly care about that.