dev-arm: Adjust idreg value in RealViewCtrl

dev-arm: Adjust idreg value in RealViewCtrl

This is to match the FVP Foundation platform.
Priviledged software could query the SYS_ID register in the V2m
Motherboard controller to extract platform information:

https://
static.docs.arm.com/100961/1110/armv8_a_fp_ug_100961_1110_00_en.pdf

In particular:

* SYS_ID[31:28] (REV) = Revision Number
** Value = 0x3 -> FVP Foundation v9.6

* SYS_ID[27:16] (HBI) = Board Number
** Value = 0x010 -> FVP Foundation platform

* SYS_ID[15:12] (BLD) = Which variant of the GIC memory is implemented
in the model
** Value = 0x1 -> (!= legacy VE memory map)

* SYS_ID[11:8] (Arch) = Architecture
** Value = 0x1 -> Architectural model (FVP)

Change-Id: Ib9395eb872cb925c029077acfdd18e48478f779b
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/+/27184
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Tested-by: kokoro <noreply+kokoro@google.com>