[Bug] - Ikea Blinds - Homekit state does not change and the update icon is always shown.
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**Describe the bug**
Ikea Blinds - Homekit state does not change and the update icon is always shown.

**Related devices**
IKEA FYRTUR roller blind

**To Reproduce**
When I activate a flow via Node Red, the Ikea blinds change as desired. But in Homebridge and especially in Homekit the state does not change and the update icon is always shown.

**Expected behavior**
Homekit should display the correct status and correct value

**MQTT messages**
When I look at the debug, there is something wrong with the passing of CurrentPosition and TargetPosition.
The TargetPosition is always the same whether I send the value 20 or 90. Therefore, it seems that the correct status is not displayed in Homekit.
![Homebridge Value send via NodeRed flow](https://user-images.githubusercontent.com/41958506/119569862-9e700500-bdaf-11eb-82d8-16d17ff8fbf7.png)

when I control the roller blind directly in Homekit I see the following
![Homebridge Value Request via Homekit (1)](https://user-images.githubusercontent.com/41958506/119569885-a92a9a00-bdaf-11eb-9ee0-f5003aed8d76.png)
![Homebridge Value Request via Homekit (2)](https://user-images.githubusercontent.com/41958506/119569891-ab8cf400-bdaf-11eb-92cd-a35d5025fe8d.png)

first image is position changed via Node Red and what arrives in Homebridge.

Second and third image is what arrives at Homebridge when I change the position via Homekit.

In both cases I set the values 20 and 90 - but in picture 1 the TargetPosition is always 100 when i send a new position via Node Red. (TargetPosition 100 was the last change via Homekit)

 think here, via z2m, the TargetPosition must have the same value as CurrentPosition.

**Versions used**
Please provide the version of the following pieces of software:
 - homebridge-z2m v1.2.0
 - Homebridge v1.3.4
 - Zigbee2MQTT 1.18.1-1
