KVM: arm/arm64: vgic-its: Free caches when GITS_BASER Valid bit is cleared

When the GITS_BASER<n>.Valid gets cleared, the data structures in
guest RAM are not valid anymore. The device, collection
and LPI lists stored in the in-kernel ITS represent the same
information in some form of cache. So let's void the cache.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>