SUNRPC: Fix a compiler warning in fs/nfs/clnt.c

Fix the report:

net/sunrpc/clnt.c:2580:1: warning: ‘static’ is not at beginning of declaration [-Wold-style-declaration]
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

net/sunrpc/clnt.c

@@ -2558,7 +2558,7 @@ static void rpc_cb_add_xprt_release(void *calldata)
 	kfree(data);
 }
 
-const static struct rpc_call_ops rpc_cb_add_xprt_call_ops = {
+static const struct rpc_call_ops rpc_cb_add_xprt_call_ops = {
 	.rpc_call_done = rpc_cb_add_xprt_done,
 	.rpc_release = rpc_cb_add_xprt_release,
 };