Merge pull request #4831 from chenyingchun0312/master

[bsp/nrf5x] fix gcc compile exception and add onchip filesystem

Author: BernardXiong

bsp/nrf5x/libraries/drivers/drv_uart.c

@@ -250,5 +250,4 @@ int rt_hw_uart_init(void)
 #endif  /* BSP_USING_UART0 */
 
 }
-INIT_BOARD_EXPORT(rt_hw_uart_init);
 #endif /* BSP_USING_UART */

bsp/nrf5x/libraries/drivers/drv_uart.h

@@ -11,8 +11,7 @@
 
 #define UART0_RB_SIZE        1024
 
-// #define USE_UART0_1         0
-
+int rt_hw_uart_init(void);
 
 #endif