efi_loader: Expose U-Boot addresses in memory map for sandbox

efi_loader: Expose U-Boot addresses in memory map for sandbox

We currently expose host addresses in the EFI memory map. That can be
bad if we ever want to use sandbox to boot strap a real kernel, because
then the kernel would fetch its memory table from our host virtual address
map. But to make that use case work, we would need to have full control
over the address space the EFI application sees.

So let's expose only U-Boot addresses to the guest until we get to the
point of allocation. EFI's allocation functions are fun - they can take
U-Boot addresses as input values for hints and return host addresses as
allocation results through the same uint64_t * parameter. So we need to
be extra careful on what to pass in when.

With this patch I am successfully able to run the efi selftest suite as
well as grub.efi on aarch64.

Signed-off-by: Alexander Graf <agraf@suse.de>