s390/zcrypt: simplify message type handling

Now that the message type modules are linked with the zcrypt_api
into a single module the zcrypt_ops_list is initialized by
the module init function of the zcyppt.ko module. After that
the list is static and all message types are present.

Drop the zcrypt_ops_list_lock spinlock and the module handling
in regard to the message types.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>