mboot64: toying around.

The sys cfg space is mostly 0xdeaddead, but we can power off the sim.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: use the existing pl01x driver.

Didn't see one already being present. Get the old
one to compile and use it instead.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: Resurrect disk/partition stuff + PL180 from U-Boot.

Well, I was afraid this moment would come - when I would regret
I didn't start working on top of u-boot.

Got it to compile. You might ask why I added PL180 if the FM
has virtio? The AEM uses the PL180.

Still needs a lot of work to even try using the PL180, and then
I'll need some SError guard code to probe it on FM without
dying.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>