AP_NavEKF3: flowDataToFuse moved to local variable

This variable is never used outside the SelectFlowFusion() method
This variable is always updated at the top of the function meaning subsequent calls to the function will always overwrite its previous value

libraries/AP_NavEKF3/AP_NavEKF3_OptFlowFusion.cpp

@@ -31,7 +31,7 @@ void NavEKF3_core::SelectFlowFusion()
     }
 
     // Check for data at the fusion time horizon
-    flowDataToFuse = storedOF.recall(ofDataDelayed, imuDataDelayed.time_ms);
+    const bool flowDataToFuse = storedOF.recall(ofDataDelayed, imuDataDelayed.time_ms);
 
     // Perform Data Checks
     // Check if the optical flow data is still valid
@@ -63,8 +63,6 @@ void NavEKF3_core::SelectFlowFusion()
             // Fuse the optical flow X and Y axis data into the main filter sequentially
             FuseOptFlow();
         }
-        // reset flag to indicate that no new flow data is available for fusion
-        flowDataToFuse = false;
     }
 
     // stop the performance timer

libraries/AP_NavEKF3/AP_NavEKF3_core.h

@@ -1195,7 +1195,6 @@ private:
     of_elements ofDataNew;          // OF data at the current time horizon
     of_elements ofDataDelayed;      // OF data at the fusion time horizon
     uint8_t ofStoreIndex;           // OF data storage index
-    bool flowDataToFuse;            // true when optical flow data has is ready for fusion
     bool flowDataValid;             // true while optical flow data is still fresh
     Vector2f auxFlowObsInnov;       // optical flow rate innovation from 1-state terrain offset estimator
     uint32_t flowValidMeaTime_ms;   // time stamp from latest valid flow measurement (msec)