s390/zcrypt: use kzalloc

This patch fixes below warning reported by coccicheck

drivers/s390/crypto/zcrypt_ep11misc.c:198:8-15: WARNING:
kzalloc should be used for cprb, instead of kmalloc/memset

Link: https://lkml.kernel.org/r/1587472548-105240-1-git-send-email-zou_wei@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

drivers/s390/crypto/zcrypt_ep11misc.c

@@ -195,11 +195,10 @@ static inline struct ep11_cprb *alloc_cprb(size_t payload_len)
 	size_t len = sizeof(struct ep11_cprb) + payload_len;
 	struct ep11_cprb *cprb;
 
-	cprb = kmalloc(len, GFP_KERNEL);
+	cprb = kzalloc(len, GFP_KERNEL);
 	if (!cprb)
 		return NULL;
 
-	memset(cprb, 0, len);
 	cprb->cprb_len = sizeof(struct ep11_cprb);
 	cprb->cprb_ver_id = 0x04;
 	memcpy(cprb->func_id, "T4", 2);