s390/pkey: make pkey_init() static

drivers/s390/crypto/pkey_api.c:1197:12:
  warning: symbol 'pkey_init' was not declared. Should it be static?
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/crypto/pkey_api.c

@@ -1194,7 +1194,7 @@ static struct miscdevice pkey_dev = {
 /*
  * Module init
  */
-int __init pkey_init(void)
+static int __init pkey_init(void)
 {
 	cpacf_mask_t pckmo_functions;