KVM: arm64: Flush/sync debug state in protected mode

The recent changes to debug state management broke self-hosted debug for
guests when running in protected mode, since both the debug owner and
the debug state itself aren't shared with the hyp's view of the vcpu.

Fix it by flushing/syncing the relevant bits with the hyp vcpu.

Fixes: beb470d9 ("KVM: arm64: Use debug_owner to track if debug regs need save/restore")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/kvmarm/5f62740f-a065-42d9-9f56-8fb648b9c63f@sirena.org.uk/


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250131222922.1548780-3-oliver.upton@linux.dev


Signed-off-by: Marc Zyngier <maz@kernel.org>