poll: add poll_notify() api and call it in all drivers

Signed-off-by: wangbowen6 <wangbowen6@xiaomi.com>

drivers/net/telnet.c

@@ -1247,11 +1247,7 @@ static int telnet_poll(FAR struct file *filep, FAR struct pollfd *fds,
     {
       /* Yes.. then signal the poll logic */
 
-      fds->revents |= (POLLRDNORM & fds->events);
-      if (fds->revents)
-        {
-          nxsem_post(fds->sem);
-        }
+      poll_notify(&fds, 1, POLLRDNORM);
     }
 
   /* Then let psock_poll() do the heavy lifting */