Berry Leds matrix alternate more and error about 'bri' attribute

[s-hadinger]

Description:

Fix errors in Leds Matrix:

• fix error about non-existent 'bri' attribute
• fix calculation of coordinates with alternate displays (thanks @Staars)

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.2.7.6
• The code change is tested and works with Tasmota core ESP32 V.3.0.0
• I accept the CLA.

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