mboot64: commit ACPI table definitions.

Did you know that ACPI 5.0 *does* spell out GIC/distributor
bindings for ARM?

I didn't.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: expose some tables.

Well, just our sorta-SPCR.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: improve exception dumping.

Am I ever adding a stack walk?

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: Make mon code conditional.

Ugh makefiles ugh.

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