fliter out the wrong result from adjust fan code

driver-avalon.c

@@ -948,6 +948,7 @@ static int64_t avalon_scanhash(struct thr_info *thr)
 
 	avalon_rotate_array(avalon);
 
+	if (hash_count) {
 		record_temp_fan(info, &ar, &(avalon->temp));
 		applog(LOG_INFO,
 		       "Avalon: Fan1: %d/m, Fan2: %d/m, Fan3: %d/m\t"
@@ -963,6 +964,7 @@ static int64_t avalon_scanhash(struct thr_info *thr)
 			info->temp_history_index = 0;
 			info->temp_sum = 0;
 		}
+	}
 
 	/* This hashmeter is just a utility counter based on returned shares */
 	return hash_count;