Nest some more namespaces

Did someone previously suggest that all namespace had been
nested?  Silly.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I22278c1caaeba8b47dc46fb2ed3078c20a11e190
diff --git a/aos/network/sctp_lib.h b/aos/network/sctp_lib.h
index 0d021a9..3430be8 100644
--- a/aos/network/sctp_lib.h
+++ b/aos/network/sctp_lib.h
@@ -19,8 +19,7 @@
 
 #define HAS_SCTP_AUTH LINUX_VERSION_CODE >= KERNEL_VERSION(5, 4, 0)
 
-namespace aos {
-namespace message_bridge {
+namespace aos::message_bridge {
 
 constexpr bool HasSctpAuth() { return HAS_SCTP_AUTH; }
 
@@ -202,7 +201,6 @@
 // Returns the max network buffer available for writing for a socket.
 size_t ReadWMemMax();
 
-}  // namespace message_bridge
-}  // namespace aos
+}  // namespace aos::message_bridge
 
 #endif  // AOS_NETWORK_SCTP_LIB_H_