Include choices params even for non editable fields

[ticosax]

The choices param can be usefull to populate list of possible values and to instantiate a ChoiceField on the serializer, even when the field is non_editable.

Relevant for the live doc and the OpenAPI integration.

Description

The fix consist into moving the choices kwargs populating step, before the early return for non_editable fields.
just before:

 if isinstance(model_field, models.AutoField) or not model_field.editable:
     kwargs['read_only'] = True
     return kwargs

[anoop-dryad]

Please disregard my approval (I can't undo it apparently) I thought I was working on another repo.