dev-arm: Add named variable for GICD_TYPER.IDBits

This could be used by other GICv3 components to query the maximum
number of implemented interrupt identifiers

Change-Id: I132e50de331aea22523260bcefba7e961b53eccd
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18599
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed