GCS_MAVLink: coverity scan - computed value overwritten without use for SITL

- when building for SITL we should just skip the num_sends work instead of overwriting the value

libraries/GCS_MAVLink/GCS_Logs.cpp

@@ -151,21 +151,22 @@ void GCS_MAVLINK::handle_log_send(DataFlash_Class &dataflash)
     if (!_log_sending) {
         return;
     }
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+    // assume USB speeds in SITL for the purposes of log download
+    const uint8_t num_sends = 40;
+#else
     uint8_t num_sends = 1;
     if (chan == MAVLINK_COMM_0 && hal.gpio->usb_connected()) {
         // when on USB we can send a lot more data
         num_sends = 40;
     } else if (have_flow_control()) {
-#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+    #if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
         num_sends = 80;
-#else
+    #else
         num_sends = 10;
-#endif
+    #endif
     }
-
-#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
-    // assume USB speeds in SITL for the purposes of log download
-    num_sends = 40;
 #endif
 
     for (uint8_t i=0; i<num_sends; i++) {