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 <[email protected]>
Reviewed-by: Harald Freudenberger <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Heiko Carstens <[email protected]>

Author: Wang Ming

arch/s390/crypto/paes_s390.c

@@ -103,7 +103,7 @@ static inline void _free_kb_keybuf(struct key_blob *kb)
 {
 	if (kb->key && kb->key != kb->keybuf
 	    && kb->keylen > sizeof(kb->keybuf)) {
-		kfree(kb->key);
+		kfree_sensitive(kb->key);
 		kb->key = NULL;
 	}
 }