SUNRPC: Clean up rpc credential initialisation

Add a helper rpc_cred_init()

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index e606c28..d5bfc67 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -127,6 +127,7 @@
 struct rpc_auth *	rpcauth_create(rpc_authflavor_t, struct rpc_clnt *);
 void			rpcauth_release(struct rpc_auth *);
 struct rpc_cred *	rpcauth_lookup_credcache(struct rpc_auth *, struct auth_cred *, int);
+void			rpcauth_init_cred(struct rpc_cred *, const struct auth_cred *, struct rpc_auth *, const struct rpc_credops *);
 struct rpc_cred *	rpcauth_lookupcred(struct rpc_auth *, int);
 struct rpc_cred *	rpcauth_bindcred(struct rpc_task *);
 void			rpcauth_holdcred(struct rpc_task *);