sched/mqueue: configurable mqueue notification

Add a configuration to disable the mqueue notification mechanism

Signed-off-by: chao.an <anchao@xiaomi.com>

include/nuttx/mqueue.h

@@ -97,9 +97,11 @@ struct mqueue_inode_s
 #else
   uint16_t maxmsgsize;        /* Max size of message in message queue */
 #endif
+#ifndef CONFIG_DISABLE_MQUEUE_NOTIFICATION
   pid_t ntpid;                /* Notification: Receiving Task's PID */
   struct sigevent ntevent;    /* Notification description */
   struct sigwork_s ntwork;    /* Notification work */
+#endif
   FAR struct pollfd *fds[CONFIG_FS_MQUEUE_NPOLLWAITERS];
 };