AP_InternalError: added spi timeout error

libraries/AP_InternalError/AP_InternalError.h

@@ -47,6 +47,7 @@ public:
         watchdog_reset              = (1U << 11),
         iomcu_reset                 = (1U << 12),
         iomcu_fail                  = (1U << 13),
+        spi_fail                    = (1U << 14),
     };
 
     void error(const AP_InternalError::error_t error);