keys: fix trusted/encrypted keys sparse rcu_assign_pointer messages

Define rcu_assign_keypointer(), which uses the key payload.rcudata instead
of payload.data, to resolve the CONFIG_SPARSE_RCU_POINTER message:
"incompatible types in comparison expression (different address spaces)"

Replace the rcu_assign_pointer() calls in encrypted/trusted keys with
rcu_assign_keypointer().

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/keys/encrypted-keys/masterkey_trusted.c b/security/keys/encrypted-keys/masterkey_trusted.c
index df87272..8c16c3e 100644
--- a/security/keys/encrypted-keys/masterkey_trusted.c
+++ b/security/keys/encrypted-keys/masterkey_trusted.c
@@ -18,6 +18,8 @@
 #include <linux/module.h>
 #include <linux/err.h>
 #include <keys/trusted-type.h>
+#include <keys/encrypted-type.h>
+#include "encrypted.h"
 
 /*
  * request_trusted_key - request the trusted key