pijuice driver uses status_set() unidiomatically

[jimklimov]

The method is intended to set individual statuses and takes care of concatenating them into the ultimate ups.status string when flushed, so the logic should be:

• start new update loop: status_init()
• collect info from device: occasionally status_set("TOKEN")
• finally: status_commit() to finalize the ups.status

In this driver I see "manual" preparation of a status_buf[] and then passing it to status_set(), which is not idiomatic and can forfeit some sanity checks done in these methods.