Input: Add Synaptics NavPoint (PXA27x SSP/SPI) driver

This driver adds support for the Synaptics NavPoint touchpad connected
to a PXA27x SSP port in SPI slave mode. The device emulates a mouse;
a tap or tap-and-a-half drag gesture emulates the left mouse button.
For example, use the xf86-input-evdev driver for an X pointing device.

Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
Tested-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>