feat(gicv3): introduce GIC component identification

The GIC specification describes ID registers in each GIC register frame
(PIDRx), which can be used to identify a GIC component. The Arm Ltd. GIC
implementations use certain ID values to identify the distributor, the
redistributors and other parts like ITSes.

Introduce a function that reads those part number IDs, which are spread
over two registers. The actual numbers are only meaningful in connection
with a certain GIC model, which would need to be checked beforehand, by
the caller.

Change-Id: Ia6ff326a1e8b12664e4637bc8e2683d2b5c7721c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
3 files changed