arm: prepare port for 48 bit PARange support

arm: prepare port for 48 bit PARange support

We currently support 3 levels of page tables for a 39 bits PA range
on ARM. This patch implements support for 4 level page tables,
and 3 level page tables with a concatenated level 1 root page
table.

On AArch32 we stick with the current restriction of building for
a 39 bit physical address space; however this change will allow
us to support a 40 to 48 bit PARange on AArch64.

Signed-off-by: Antonios Motakis <antonios.motakis@huawei.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>