AP_Airspeed: rename get_health_failure_probability to get_health_probability

libraries/AP_Airspeed/AP_Airspeed.cpp

@@ -689,7 +689,7 @@ void AP_Airspeed::Log_Airspeed()
             offset        : get_offset(i),
             use           : use(i),
             healthy       : healthy(i),
-            health_prob   : get_health_failure_probability(i),
+            health_prob   : get_health_probability(i),
             primary       : get_primary()
         };
         AP::logger().WriteBlock(&pkt, sizeof(pkt));

libraries/AP_Airspeed/AP_Airspeed.h

@@ -266,12 +266,12 @@ private:
     // returns 0 if the sensor is not enabled
     float get_pressure(uint8_t i);
 
-    // get the failure health probability
-    float get_health_failure_probability(uint8_t i) const {
+    // get the health probability
+    float get_health_probability(uint8_t i) const {
         return state[i].failures.health_probability;
     }
-    float get_health_failure_probability(void) const {
-        return get_health_failure_probability(primary);
+    float get_health_probability(void) const {
+        return get_health_probability(primary);
     }
 
     void update_calibration(uint8_t i, float raw_pressure);