Introduce qoriq_gpio_pic driver

It adds the PIC functionality on top of qoriq_gpio driver.
We need a separate module since the powerpc PIC API is completely
different than on other architectures.

Two types of intr_map_data are supported:
INTR_MAP_DATA_GPIO and INTR_MAP_DATA_FDT.

This way interrupts can be allocated using the userspace gpio
interrupt allocation method, as well as directly from simplebus.
The latter can be used by devices that have its irq routed to a GPIO pin.

Obtained from: Semihalf
Sponsored by: Alstom Group