s390: use false/true when using bool

Yet another trivial patch to reduce the noise that coccinelle
generates.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 51eece9..919f7aa 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -201,7 +201,7 @@ static inline bool zcrypt_card_compare(struct zcrypt_card *zc,
 				       unsigned weight, unsigned pref_weight)
 {
 	if (!pref_zc)
-		return 0;
+		return false;
 	weight += atomic_read(&zc->load);
 	pref_weight += atomic_read(&pref_zc->load);
 	if (weight == pref_weight)
@@ -215,7 +215,7 @@ static inline bool zcrypt_queue_compare(struct zcrypt_queue *zq,
 					unsigned weight, unsigned pref_weight)
 {
 	if (!pref_zq)
-		return 0;
+		return false;
 	weight += atomic_read(&zq->load);
 	pref_weight += atomic_read(&pref_zq->load);
 	if (weight == pref_weight)