Allowed to remove IP address while connected to device

Found issue:

User is allowed to remove the device IP in Android Connector while connected to device. Disconnecting wont' succeed then unless correct IP is retyped.

Steps to reproduce:

1. Open Design Studio and some project
2. Open Android Connector (File -> Deploy Project to Android)
3. Open Qt UI Viewer
4. Go to Menu -> Network
5. In DS, type the local IP seen in Qt UI Viewer to Device IP field
6. Click Connect
7. After successful connection, remove IP from Device IP field
8. Click Disconnect
9. -> Connection is not closed. Qt UI Viewer/Network page shows only "Design Studio is connected. Waiting for project..." but not the IP address anymore to quickly check and retype it to disconnect.
10. -> Would expect that user cannot delete the IP address once connected to device, only after disconnecting the device.