nmofono: increase the wait time for the hotspot connection to activate

Seems like on some devices (e.g. original Volla Phone) it needs just a little bit of extra time time to activate the NM connection for hotspot. So give it that time by increasing the sleep between the checks.

Fixes ubports/porting/reference-device-ports/android9/volla-phone/volla-yggdrasil#3 (closed), fixes ubports/porting/reference-device-ports/android10/volla-phone-x/volla-yggdrasilx#6 (closed).