dev-arm: Rewrite GICv3 update

dev-arm: Rewrite GICv3 update

The GICv3 update methods are method which are invoked anytime the model
needs to evaluate a change in its state, which most of the time means
managing the state of an interrupt (forwarding it to a PE, deasserting
it, etc).
The way it is currently done is a little bit obscure and doesn't
handle correctly IRQ prioritization.
Example:
An IRQ which is handled by the redistributor (PPI or LPI) was not
competing with any pending interrupts coming from the distributor (SPIs)
once raised by a peripheral.

Also the way the pending state of an interrupt was removed at the
cpu interface level wasn't happening in place where this was actually
happening (E.g. when activating it), but happened with a weird
fullUpdate semantic, where if there was a pending interrupt in a
cpu interface, all cpu interfaces had their pending interrupt (if any)
been disabled.

With this patch, state update always starts at the distributor, and
it goes down until the cpu interface where a Gicv3CPUInterface::update
method selects the winning interrupt coming from distributor/redistributor
to be forwarded to the PE.

Change-Id: I1c517cbc4bf107cc2d7ae7beb2692e3cf5187a40
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/+/20614
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>