DeskClock: Fix wrong screensaver clock style being displayed

* Similar to commit e96455ab, the preference didn't reflect the actual
  value
* Get the value from settings manually and assign the preference the
  correct index and summary

Fixes: https://gitlab.com/LineageOS/issues/android/-/issues/5918
Change-Id: I07a5f2478149bd106c4fd48ccb6f218b37f21362