Fix buttonevent values
Fix buttonevent values

Use `buttonevent` values consistent with other switches:
- Continue numbering buttons across endpoints;
- DimUp = 200x; DimDown = 300x.

dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin