ios: create devices in the disconnected state

The device status is updated only when it is connected or disconnected.
Thus a restored device would mantain the unknown state in which the user
cannot remove the device.
Using always the disconnected state so the use can remove the devices.

Change-Id: Icdeb1e314eef0e5b1553decfc728e4b9eab939ab
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>