Set predefined logical touchpad sizes for several ancient Elan hw v.2
models. This change is based on Linux driver.
Determine logical trace size. It used for calculation of touch sizes
in surface units for MT-protocol type B evdev reports.

Reviewed by: gonzo
Approved by: gonzo (mentor)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D10266