arch-arm: Implement ARMv8.1-HPD, Hierarchical permission disable

arch-arm: Implement ARMv8.1-HPD, Hierarchical permission disable

According to the armarm:
ARMv8.1-HPD introduces the facility to disable the hierarchical
attributes, APTable, PXNTable, and UXNTable, in the translation tables.
This disable has no effect on the NSTable bit.  This feature is
mandatory in ARMv8.1 implementations.

This feature is added only to the VMSAv8-64 translation regimes. ARMv8.2
extends this to the AArch32 translation regimes, see ARMv8.2-AA32HPD.

The ID_AA64MMFR1_EL1.HPDS field identifies the support for ARMv8.1-HPD.

Change-Id: Ibbf589b82f2c1e4437b43252f8f633e8f6fb0b80
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19610
Tested-by: kokoro <noreply+kokoro@google.com>