CameraBin: do fetch viewfinder settings even after LoadedStatus

Commit 84d0d876

 (CameraBin: Postpone
fetching supported viewfinder settings) checks if the camera is in
LoadedStatus before fetching supported viewfinder settings. However, if
viewfinder settings is never requested or not (yet) available during
LoadedStatus, it won't try to fetch it at e.g. ActiveStatus. In that
case, requesting supported viewfinder settings never works.

[ChangeLog][CameraBin] CameraBin plugin now fetches supported viewfinder
settings at status higher or equal to LoadedStatus if it has not been
fetched.

Change-Id: Ibd32c25feac9b1a133945e754d26181937190a24
Reviewed-by: VaL Doroshchuk <valentyn.doroshchuk@qt.io>