Add missing flow form field translations in sma

The `sma` integration has flow form fields missing translations in `strings.json`. **Violations:** - [`config_flow.py:208`](https://github.com/home-assistant/core/blob/851ddc3ee3cc2d12a8b5b934838f61dbcf695893/homeassistant/components/sma/config_flow.py#L208) **How to fix:** Add the missing field names to the `data` section of the relevant step in `strings.json`. After fixing, remove the `# pylint: disable-next` comment. Part of home-assistant/epics#76