SUNRPC: Replace clnt->cl_principal

The clnt->cl_principal is being used exclusively to store the service
target name for RPCSEC_GSS/krb5 callbacks. Replace it with something that
is stored only in the RPCSEC_GSS-specific code.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/auth_null.c b/net/sunrpc/auth_null.c
index a5c36c0..4664eb4 100644
--- a/net/sunrpc/auth_null.c
+++ b/net/sunrpc/auth_null.c
@@ -18,7 +18,7 @@
 static struct rpc_cred null_cred;
 
 static struct rpc_auth *
-nul_create(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
+nul_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
 {
 	atomic_inc(&null_auth.au_count);
 	return &null_auth;