atkbdc - Do not attach PS2 controller via legacy ISA bus, if FADT says so.
* If the FADT BootFlags value tells us that we shouldn't expect the PS2
controller to be at the IO ports 0x60/0x64, we should instead only attach
the atkbdc driver when there is a matching device in the ACPI namespace.
* This avoids attempts to attach the atkbdc PS2 controller driver on
hardware which doesn't have a usable PS2 controller. This happens on
many modern notebooks, and has been the case for some time on desktop
hardware that doesn't provide an emulated PS2 controller for using USB
input devices all the time (it either is never initialized, or might
get disabled by some of the ACPI or USB initialization during bootup).
UnifiedSplitRaw
