s390/zcrypt: Fix CCA cipher key gen with clear key value function

Regression tests showed that the CCA cipher key function which
generates an CCA cipher key with given clear key value does not work
correctly. At parsing the reply CPRB two limits are wrong calculated
resulting in rejecting the reply as invalid with s390dbf message
"_ip_cprb_helper reply with invalid or unknown key block".

Fixes: f2bbc96e ("s390/pkey: add CCA AES cipher key support")
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>