fix(bw): customisable switch LED color text sometimes incorrect on GX12

[philmoz]

Fixes a number of issues with the way the colors are handled for the custom switches on the GX12:

• Default ON color is 'white'; but shows as 'blue' when viewed in model settings.
• If a custom value is set manually in the model file the color is shown as 'blue' instead of 'custom' in model settings.