pxa2xx_pic: update to use qdev

Use qdev/sysbus framework to handle pxa2xx-pic. Instead of exposing IRQs
via array, reference them via qdev_get_gpio_in().

Patch has been modified by the committer.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Andrzej Zaborowski <andrew.zaborowski@intel.com>
