Berry Zigbee fix attributes

[s-hadinger]

Description:

This is linked to a remaining bug in Berry walrus operator. Fixing for now by avoiding the walrus operator.

Related issue (if applicable): fixes #22623

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.8
• The code change is tested and works with Tasmota core ESP32 V.3.1.0.241206
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass