Input: psmouse - add support for Elantech touchpads

This is version 5 of the driver. Relative mode support has been
dropped (users wishing to use touchpad in relative mode can use
standard PS/2 protocol emulation done in hardware). The driver
supports both original version of Elantech protocol and the newer
one used by touchpads installed in EeePC.

Signed-off-by: Arjan Opmeer <[email protected]>
Signed-off-by: Dmitry Torokhov <[email protected]>

Author: adopmeer