KVM: arm64: GICv2: Handle deactivation via GICV_DIR traps

KVM: arm64: GICv2: Handle deactivation via GICV_DIR traps

Add the plumbing of GICv2 interrupt deactivation via GICV_DIR.
This requires adding a new device so that we can easily decode
the DIR address.

The deactivation itself is very similar to the GICv3 version.

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://msgid.link/20251120172540.2267180-39-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>