remove unused variable

Author: huiruan

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/FlushRegionCallable.java

@@ -49,7 +49,6 @@ protected void doCall() throws Exception {
     LOG.debug("Starting region operation on {}", region);
     region.startRegionOperation();
     try {
-      long readPt = region.getReadPoint(IsolationLevel.READ_COMMITTED);
       HRegion.FlushResult res;
       if (columnFamily == null) {
         res = region.flush(true);