Tidy other comments.
open_drive: don't call set_drive_state if we decide to take it down.
This could help avoid some race conditions with the daemon.
init_drive: don't set the drive down, we'll let close_locked_drive do
that.
close_locked_drive: set drive state to down without calling
set_drive_state. This could help avoid some race conditions with the
daemon.
driveio: remove the function, it wasn't being used.
get_volume_label: remove volume dependencies so that we can return a
label for plexes and subdisks as well. What a kludge.