LED Class brightness_hw_changed attribute support

configname: CONFIG_LEDS_BRIGHTNESS_HW_CHANGED

Linux Kernel Configuration
└─>Device Drivers
└─>LED Support
└─>LED Class brightness_hw_changed attribute support
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This option enables support for the brightness_hw_changed attribute
for LED sysfs class devices under /sys/class/leds.

See Documentation/ABI/testing/sysfs-class-led for details.