Input: add driver for Altera PS/2 controller

This patch adds a new SERIO driver to support the Altera University
Program PS/2 controller.

[dtor@mail.ru: assorted cleanups]
Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>