YX-025WB aroma diffuser: rename config file.

To avoid issues on case insensitive filesystems and differences
between HA slugified device name and filename, only lower case,
numbers and underscores are used in filenames by convention.

Also most widely used convention is brand_model_devicetype, since
this is unbranded, combine model and device type into single words.

PR #2204 / Issue #2182