Input: serio - add support for Alwinner A10/A20 PS/2 controller

This driver implements support for PS2 controller found on Allwinner A10,
A20 SOCs. It has been tested on A20 Olimex-Lime2 board and also on A10.

Signed-off-by: Vishnu Patekar <vishnupatekar0510@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>