s390x: add parallel skey migration test

Right now, we have a test which sets storage keys, then migrates the VM
and - after migration finished - verifies the skeys are still there.

Add a new version of the test which changes storage keys while the
migration is in progress. This is achieved by adding a command line
argument to the existing migration-skey test.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20221220083030.30153-2-nrb@linux.ibm.com


Message-Id: <20221220083030.30153-2-nrb@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>