tests: fix I/O test for hosts defaulting to LUKSv2

tests: fix I/O test for hosts defaulting to LUKSv2

Some distros are now defaulting to LUKS version 2 which QEMU cannot
process. For our I/O test that validates interoperability between the
kernel/cryptsetup and QEMU, we need to explicitly ask for version 1
of the LUKS format.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20190927101155.25896-1-berrange@redhat.com
Tested-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>