Kobo: Unbreak a slew of devices (#10019)

Fix #10020, Regression since #10008

(hasMultiTouch is set by `Generic.init`, but we use it before that;
so just set it properly ourselves in our superclass, because we don't
actually need to rely on Generic's autodetection).

frontend/device/kobo/device.lua

@@ -144,6 +144,8 @@ local Kobo = Generic:extend{
     canPowerOff = yes,
     canSuspend = yes,
     supportsScreensaver = yes,
+    -- most Kobos are MT-capable
+    hasMultitouch = yes,
     -- most Kobos have X/Y switched for the touch screen
     touch_switch_xy = true,
     -- most Kobos have also mirrored X coordinates