(1) Support NK-N9H30 board. (2) Change Mutex's flag to RT_IPC_FLAG_PRIO from RT_IPC_FLAG_FIFO.
1. NUC980 platform: USBH, INPUTCAPTURE, SPINAND. 2. Correct enter-quad-mode routine in board_dec.c. 3. Use RT_ASSERT to catch system-call-exceptions.