Revert to RT_IPC_FLAG_PRIO.

components/drivers/sdio/mmcsd_core.c

@@ -711,7 +711,7 @@ struct rt_mmcsd_host *mmcsd_alloc_host(void)
     host->id = allocated_host_num;
     allocated_host_num++;
 
-    rt_mutex_init(&host->bus_lock, "sd_bus_lock", RT_IPC_FLAG_FIFO);
+    rt_mutex_init(&host->bus_lock, "sd_bus_lock", RT_IPC_FLAG_PRIO);
     rt_sem_init(&host->sem_ack, "sd_ack", 0, RT_IPC_FLAG_FIFO);
 
     return host;