s390:criu: Add support for s390 consoles

On s390 we have special console drivers with minors 64 and 65.
Add support for them in criu code and in zdtm testsuite.

Reviewed-by: Alice Frosi <alice@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>