QLowEnergyController - service state (OS X/iOS)

Fix a bug - call setState on a service instead of stateChanged (which is
just a signal not actually chanding the service's state).

Change-Id: I243f1f6c6775a5592357a443a2f180e4afcf8219
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>