Xorg device disabled with 'Option "Ignore" "true"' still enabled by udev+Xorg. How to fix?

[Weiwu Zhang]

Hi, I'm running Ubuntu 15.04,
$ uname -r
3.13.0-39-generic

With X.Org X Server 1.17.1

My touch-screen is broken and ghosts fake signals. It's been disabled in 
Windows 8 but I can't find a way to disable it in Ubuntu except runnig 
such commands every time I login:
$ xinput set-prop 12 "Device Enabled" 0

The default /usr/share/X11/xorg.conf.d/10-evdev.conf I changed to:

...
Section "InputClass"
         Identifier "evdev touchpad catchall"
         MatchIsTouchpad "on"
         MatchDevicePath "/dev/input/event*"
         Option "Ignore" "True"
         Driver "evdev"
EndSection
...

I also tried to delete the Driver line, change it to strange values like 
"vmmouse", or change the word Driver to MatchDriver, or making xorg.conf 
with this section copied over. None of them works. xinput consistantly is 
able to list the touchscreen device and react to ghost signals:

$ xinput ⎡ Virtual core pointer                    	id=2	[master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer              	id=4	[slave  pointer  (2)]
⎜   ↳ ASUS Tech Inc. ASUS HID Device          	id=11	[slave  pointer  (2)]
⎜   ↳ Microsoft Microsoft® 2.4GHz Transceiver v8.0	id=15	[slave  pointer  (2)]
⎜   ↳ Microsoft Microsoft® 2.4GHz Transceiver v8.0	id=17	[slave  pointer  (2)]
⎜   ↳ SIS0817:00 0457:1071                    	id=12	[slave  pointer  (2)]
⎣ Virtual core keyboard                   	id=3	[master keyboard (2)]
     ↳ Virtual core XTEST keyboard             	id=5	[slave  keyboard (3)]
     ↳ Video Bus                               	id=6	[slave  keyboard (3)]
     ↳ Sleep Button                            	id=7	[slave  keyboard (3)]
     ↳ Heng Yu Technology Poker II             	id=8	[slave  keyboard (3)]
     ↳ Heng Yu Technology Poker II             	id=9	[slave  keyboard (3)]
     ↳ ASUS Tech Inc. ASUS HID Device          	id=10	[slave  keyboard (3)]
     ↳ gpio-keys                               	id=14	[slave  keyboard (3)]
     ↳ Microsoft Microsoft® 2.4GHz Transceiver v8.0	id=16	[slave  keyboard (3)]
     ↳ Asus WMI hotkeys                        	id=13	[slave  keyboard (3)]

(id=12 is the broken touch-screen).

In fact, I couldn't find "Ignore" option in evdev(4) man page, but am able to
find multiple internet posts / mails suggesting to add it.

How do I completely disable the adding of the SIS0817:00 0457:1071 and its 
use by Xorg?

Thanks a lot!