less cpu usage and set 1 as the final value

if sensor is less than 3, sets to 1.
if xfce brightness bug puts actual_brightness to 0, it will goes to 1 with less than 3 in anbient or more with greater than 3 anbient..

add service in :"/etc/systemd/system/" to auto start and auto restart if broken in e.g. suspend. Works even in the greeter.

autobright.service

@@ -0,0 +1,25 @@
+[Unit]
+
+Description=roda autobrightness com 1% de processamento
+After=multi-user.target
+After=graphical.target
+After=basic.target
+After=sysinit.target
+After=system.slice
+After=systemd-journald.socket
+After=initrd-switch-root.service
+After=iio-sensor-proxy.service
+
+
+
+[Service]
+ExecStartPre=/bin/bash -c "sleep 5"
+ExecStart=/bin/bash -c "exec /etc/luztecla/autobrightness.sh"
+
+
+Restart=always
+
+[Install]
+
+WantedBy=graphical.target
+WantedBy=multi-user.target