AP_IOMCU: Ensure IOMCU does not log if there is no logger

libraries/AP_IOMCU/AP_IOMCU.cpp

@@ -328,6 +328,7 @@ void AP_IOMCU::read_status()
     uint32_t now = AP_HAL::millis();
     if (now - last_log_ms >= 1000U) {
         last_log_ms = now;
+        if (AP_Logger::get_singleton()) {
             AP::logger().Write("IOMC", "TimeUS,Mem,TS,NPkt,Nerr,Nerr2,NDel", "QHIIIII",
                                AP_HAL::micros64(),
                                reg_status.freemem,
@@ -336,6 +337,7 @@ void AP_IOMCU::read_status()
                                total_errors,
                                reg_status.num_errors,
                                num_delayed);
+        }
 #if IOMCU_DEBUG_ENABLE
         static uint32_t last_io_print;
         if (now - last_io_print >= 5000) {