dev-arm: SMMUv3 Table walks using TnSZ

dev-arm: SMMUv3 Table walks using TnSZ

TnSZ is needed when selecting the starting level of a table
walk, since it directly affects the number of IA bits.
This has been implemented by adding T0SZ and S2T0SZ to the
translation context.
T1SZ is not used at the moment since the current model doesn't
support TTB1.

Change-Id: I75663475c4dc01e5986cd93f8deafcdf7b1ece82
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Michiel Van Tol <michiel.vantol@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19630
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>