Add an option to disable touchscreen

On last XPS 13, disabling hid_multitouch module also disable touchpad.

On Xorg, I can disable touchscreen with xinput. But on wayland, it's not possible.

It's really needed for me because many web apps and web sites disable scrollbars (Proxmox for example) when detecting a touchscreen.

And even if touchscreen is active, wayland should not report it when window is on a screen without touch capabilities (multihead).