KVM: arm64: vgic-its: Walk LPI xarray in its_sync_lpi_pending_table()

The new LPI xarray makes it possible to walk the VM's LPIs without
holding a lock, meaning that vgic_copy_lpi_list() is no longer
necessary. Prepare for the deletion by walking the LPI xarray directly
in its_sync_lpi_pending_table().

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-3-oliver.upton@linux.dev


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