sunxi: Enabled gpiolib

Added missing header files and config options to enable
gpiolib support with sysfs

Signed-off-by: Alexandr V. Shutko <alex@shutko.ru>
Added gpio driver for sunxi platform

This is gpio driver for sunxi platform. It based on gpiolib
framework and supports get/set value, change direction, poll(2)
on value (gpio irq).

Signed-off-by: Alexandr V. Shutko <alex@shutko.ru>