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