Return an error to userspace if the VM's ID register values haven't been
initialized in preparation for changing the debugfs file initialization
order.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240227094115.1723330-2-oliver.upton@linux.devSigned-off-by: Oliver Upton <oliver.upton@linux.dev>