irqchip/gic-v5: Skip deactivate for forwarded PPI interrupts

irqchip/gic-v5: Skip deactivate for forwarded PPI interrupts

If a PPI interrupt is forwarded to a guest, skip the deactivate and
only EOI. Rely on the guest deactivating both the virtual and physical
interrupts (due to ICH_LRx_EL2.HW being set) later on as part of
handling the injected interrupt. This mimics the behaviour seen on
native GICv3.

This is part of adding support for the GICv3 compatibility mode on a
GICv5 host.

Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Co-authored-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Link: https://lore.kernel.org/r/20250627100847.1022515-2-sascha.bischoff@arm.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>