The previous commit disabled sxmo_idle.sh and the idle_locker in the
unlock/lock hooks, leaving the display backlight pinned at maximum
brightness forever (Xorg runs with -s 0 -dpms and /sys/power/state is
empty, so the panel never blanks). On a phone with no suspend this is by
far the dominant battery drain.
Restore sxmo_idle.sh and start idle_locker from the unlock and lock hooks
so the screen blanks after SXMO_UNLOCK_IDLE_TIME (default 30s) / once
locked after SXMO_LOCK_IDLE_TIME (default 8s). Locking itself stays
explicit-only, matching the documented design; only the display blanks.
Verified live on the device: after the idle timeout the state transitions
to screenoff and /sys/class/backlight/backlight/brightness drops to 0.
Luxferre