KVM: selftests: arm64: Support P52V48 4K and 16K guest_modes

Add support for VM_MODE_P52V48_4K and VM_MODE_P52V48_16K guest modes by
using the FEAT_LPA2 pte format for stage1, when FEAT_LPA2 is available.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231127111737.1897081-13-ryan.roberts@arm.com