NeoPool fix possible IntegerDivideByZero

[curzon01]

Description:

This fix a possible IntegerDivideByZero crash in NeoPool sensor module, which could happen for newer Sugar Valley systems (originally posted in HA forum )

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.3.1.10 / V.3.3.7
• I accept the CLA.