Input: ALPS - add support for DualPoint device on Dell XT2 model

The device uses special MPU controller that necessitates the new
initialization sequence for the device. We also define a new protocol for
the trackpad that allows reporting better resolution than older V2
protocol.

Signed-off-by: Yunkang Tang <yunkang.tang@cn.alps.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>