can I do a restore controlfile from autobackup out FAST RECOVERY AREA?
Why not?

From Database Backup and Recovery Reference 12c:


  The default location for the autobackup on disk is the fast recovery
  area (if configured) or a platform-specific location (if not
  configured). RMAN automatically backs up the current control file
  using the default format of %F. You can change the location and file
  name format with the CONFIGURE CONTROLFILE AUTOBACKUP FORMAT and SET
  CONTROLFILE AUTOBACKUP FORMAT commands.