MFC r208162, 208836, 208837:

Program the K2 SATA controller's interrupt to be level-triggered low, and
respect the edge/level settings in the device tree.

OpenPIC on powerpc sets interrupts to be level high by default. On Apple
interrupt controllers, all level interrupts are low regardless of
programming except interrupt 0, used by K2 SATA on some Apple systems, with
the result that the K2 SATA IRQ is misconfigured. Pending review of changes
to this default, work around this by changing the programming of the K2
SATA interrupt to level low.

Approved by: re (kib)