fix #2546, change timeout of DubboInvoker from Milliseconds to Nanoseconds(#2552)

diff --git a/protocol/dubbo/dubbo_invoker.go b/protocol/dubbo/dubbo_invoker.go
index 4a633a1..51e0914 100644
--- a/protocol/dubbo/dubbo_invoker.go
+++ b/protocol/dubbo/dubbo_invoker.go
@@ -175,9 +175,9 @@
 		if len(mTimeout) != 0 {
 			timeout, _ = time.ParseDuration(mTimeout)
 		}
-		// set timeout into invocation
-		ivc.SetAttachment(constant.TimeoutKey, strconv.Itoa(int(timeout.Milliseconds())))
 	}
+	// set timeout into invocation
+	ivc.SetAttachment(constant.TimeoutKey, strconv.Itoa(int(timeout.Nanoseconds())))
 	return timeout
 }