qoriq_gpio: Implement interrupt controller functionality

The pic_* interface was used.
Only edge interrupts are supported by this controller.
Driver mutex had to be converted to a spin lock so that it can
be used in the interrupt filter context.
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
Differential revision: https://reviews.freebsd.org/D32587