[9front] wacom ps/2 devices

[sl@stanleylieber.com]

since 2005, some thinkpads have shipped with integrated, transparent
wacom tablets overlaying the screen.  the x41, x60, and x61 tablets
were all serial devices.  the x230 and x1 yoga 3rd gen tablets are usb
devices.  all of these have been previously made to work in 9front.
aiju wrote a driver[0] for the serial ones, while the usb ones "just
work" and are treated as usb mice[1].

the x1 tablet series took a different tack.  these tablets are ps/2
devices:

x1 tablet 1st/2nd gen: wacom hid 5115
x1 tablet 3rd gen: wacom hid 511a

both of these were at some point added to linuxwacom[2][3][4], and
they work fine for me with wayland under alpine linux.

where do we start to try and make these work in 9front?  i have both
machines and can hack/test/etc., but i'm a dog sitting at a keyboard
and i have no idea what i'm doing.

if this requires more than a trivial effort i am willing to put up
another bounty to fund the work.

sl

[0] http://fqa.9front.org/fqa3.html#3.2.4.1
[1] http://fqa.9front.org/fqa3.html#3.2.4.2.1
[2] https://linux-hardware.org/?id=ps/2:wacom-5115-hid-5115-pen
[3] https://linux-hardware.org/?id=ps/2:wacom-5115-hid-5115-finger
[4] https://linux-hardware.org/index.php?id=ps/2:wacom-511a-hid-511a-pen