FP4: Allow sensors hal to read backlight node

01-28 15:11:09.396   847   847 W 51_see  : type=1400 audit(0.0:326): avc: denied { read } for name="brightness" dev="sysfs" ino=47661 scontext=u:r:hal_sensors_default:s0 tcontext=u:object_r:sysfs:s0 tclass=file permissive=0