s390/crypto: use kfree_sensitive() instead of kfree()

key might contain private part of the key, so better use
kfree_sensitive() to free it.

Signed-off-by: Wang Ming <machel@vivo.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Link: https://lore.kernel.org/r/20230717094533.18418-1-machel@vivo.com


Signed-off-by: Heiko Carstens <hca@linux.ibm.com>