s390/zcrypt: Separate msgtype implementation from card modules.

Msgtype implementations are now separated from card specific modules
and can be dynamically registered. Existing msgtype implementations
are restructured in modules.

Signed-off-by: Holger Dengler <hd@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>