s390/pkey: Fix wrong handling of secure key with old MKVP

When a secure key with an old Master Key Verification
Pattern was given to the pkey_findcard function, there was
no responsible card found because only the current MKVP of
each card was compared. With this fix also the old MKVP
values are considered and so a matching card able to handle
the key is reported back to the caller.

Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>