Support screen brightness adjustment button, the KEY_BRIGHTNESS_CYCLE EV_KEY

The Acer Veriton Z4660G/Z4860G/Z6860G series AIO desktops have a brightness button in the bottom, but pressing the button does not work on Linux. According to ODM's description, a control application will popup for brightness adjustment on Windows, if the button is pressed. I have checked it with evtest:

sudo evtest 
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0:	Sleep Button
/dev/input/event1:	Power Button
/dev/input/event2:	Power Button
/dev/input/event3:	Video Bus
/dev/input/event4:	USB Optical Mouse
/dev/input/event5:	Wired USB Keyboard
/dev/input/event6:	Wired USB Keyboard System Control
/dev/input/event7:	Wired USB Keyboard Consumer Control
/dev/input/event8:	HDA Intel PCH Front Mic
/dev/input/event9:	HDA Intel PCH Front Headphone
/dev/input/event10:	HDA Intel PCH HDMI/DP,pcm=3
/dev/input/event11:	HDA Intel PCH HDMI/DP,pcm=7
/dev/input/event12:	HDA Intel PCH HDMI/DP,pcm=8
/dev/input/event13:	HDA Intel PCH HDMI/DP,pcm=9
/dev/input/event14:	HDA Intel PCH HDMI/DP,pcm=10
/dev/input/event15:	USB2.0 FHD Camera: USB2.0 FHD C
Select the device event number [0-15]: 3
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x0 product 0x6 version 0x0
Input device name: "Video Bus"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 224 (KEY_BRIGHTNESSDOWN)
    Event code 225 (KEY_BRIGHTNESSUP)
    Event code 227 (KEY_SWITCHVIDEOMODE)
    Event code 241 (KEY_VIDEO_NEXT)
    Event code 242 (KEY_VIDEO_PREV)
    Event code 243 (KEY_BRIGHTNESS_CYCLE)
    Event code 244 (KEY_BRIGHTNESS_ZERO)
    Event code 245 (KEY_DISPLAY_OFF)
Properties:
Testing ... (interrupt to exit)
Event: time 1542615014.263931, type 1 (EV_KEY), code 243 (KEY_BRIGHTNESS_CYCLE), value 1
Event: time 1542615014.263931, -------------- SYN_REPORT ------------
Event: time 1542615014.263939, type 1 (EV_KEY), code 243 (KEY_BRIGHTNESS_CYCLE), value 0
Event: time 1542615014.263939, -------------- SYN_REPORT ------------
Event: time 1542615015.380922, type 1 (EV_KEY), code 243 (KEY_BRIGHTNESS_CYCLE), value 1
Event: time 1542615015.380922, -------------- SYN_REPORT ------------
Event: time 1542615015.380930, type 1 (EV_KEY), code 243 (KEY_BRIGHTNESS_CYCLE), value 0

When the button is pressed, the code 243 (KEY_BRIGHTNESS_CYCLE) is sent. I found there are codes for screen brightness "StepUp" and "StepDown". However, it seems no related code for "Brightness Cycle" (something like that) in g-s-d now.