SUNRPC: Remove the tk_auth macro...

We should almost always be deferencing the rpc_auth struct by means of the
credential's cr_auth field instead of the rpc_clnt->cl_auth anyway. Fix up
that historical mistake, and remove the macro that propagated it.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/auth_unix.c b/net/sunrpc/auth_unix.c
index d9c50d8..5ed91e5 100644
--- a/net/sunrpc/auth_unix.c
+++ b/net/sunrpc/auth_unix.c
@@ -204,7 +204,7 @@
 		printk("RPC: giant verf size: %u\n", size);
 		return NULL;
 	}
-	task->tk_auth->au_rslack = (size >> 2) + 2;
+	task->tk_msg.rpc_cred->cr_auth->au_rslack = (size >> 2) + 2;
 	p += (size >> 2);
 
 	return p;