ARM: KVM: Add populating of fault data structure

On guest exit, we must take care of populating our fault data
structure so that the host code can handle it. This includes
resolving the IPA for permission faults, which can result in
restarting the guest.

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