One disconnected device makes all devices "no response"
<!-- Provide a general summary in the Title above -->

### Expected Behavior
<!-- If you're describing a bug, tell us what should happen -->
<!-- If you're suggesting a change/improvement, tell us how it should work -->
Only the disconnected device should be "no response" in the Home app

### Current Behavior
<!-- If describing a bug, tell us what happens instead of the expected behavior -->
<!-- If suggesting a change/improvement, explain the difference from current behavior -->
If any of the devices is unplugged, it will make not only that particular device "no response" but also everything else.

### Steps to Reproduce (for bugs)
<!-- Please add a series of steps to reproduce the problem. -->
Have more than 1 device added using the TP-Link plugin and working in the Home app, unplug any 1 device.

### Versions
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- **Node**:       `v12.16.2`
- **Homebridge**: `0.4.53`
- **OS**:         `iOS 13.4`

### Configuration
<!-- Please include the TplinkSmarthome platform section of your config.json file.
Paste between the the two ``` lines below.
-->
```json

{
    "name": "TP-Link",
    "platform": "TplinkSmarthome"
}
```

### Homebridge Log / Command Output
<!-- Paste relevant output between the two ``` lines below
  - Remove any sensitive information, passwords, etc.
  - If output is long:
    - Please extract only the relevant portions if possible (remove other plugin's output, etc)
    - Consider creating a gist, etc
  - However, please include the beginning of the log where the homebridge initialization happens if possible
-->
```
[TP-Link.API] TCP Timeout
[TP-Link.API] [Heater] device.send() Error: TCP Timeout
    at Timeout._onTimeout (/usr/lib/node_modules/homebridge-tplink-smarthome/node_modules/tplink-smarthome-api/lib/client.js:228:20)
    at listOnTimeout (internal/timers.js:549:17)
    at processTimers (internal/timers.js:492:7)
[TP-Link] [Heater] 
[TP-Link] Error: TCP Timeout
    at Timeout._onTimeout (/usr/lib/node_modules/homebridge-tplink-smarthome/node_modules/tplink-smarthome-api/lib/client.js:228:20)
    at listOnTimeout (internal/timers.js:549:17)
    at processTimers (internal/timers.js:492:7)
```
