Define a new wscons mouse type for Synaptics clickpad devices that lack

Define a new wscons mouse type for Synaptics clickpad devices that lack
physical buttons.  This will be used if the acpi pnpid for the mouse
matches a list provided by Synaptics found in Linux.

Combined with the xenocara changes this will remove the need for an xorg
config file for the x240/t440/t540 generation of thinkpads.

ok matthieu@ shadchin@ kettenis@