hbase-store: fix build error

store/hbase/snapshot.go

@@ -142,10 +142,10 @@ type hbaseIter struct {
 	valid bool
 }
 
-func (it *hbaseIter) Next() (kv.Iterator, error) {
+func (it *hbaseIter) Next() error {
 	it.rs = it.ThemisScanner.Next()
 	it.valid = it.rs != nil && len(it.rs.Columns) > 0 && !it.ThemisScanner.Closed()
-	return it, nil
+	return nil
 }
 
 func (it *hbaseIter) Valid() bool {

store/hbase/txn.go

@@ -154,7 +154,7 @@ func (txn *hbaseTxn) Delete(k kv.Key) error {
 func (txn *hbaseTxn) each(f func(kv.Iterator) error) error {
 	iter := txn.UnionStore.Dirty.NewIterator(nil)
 	defer iter.Close()
-	for ; iter.Valid(); iter, _ = iter.Next() {
+	for ; iter.Valid(); iter.Next() {
 		if err := f(iter); err != nil {
 			return errors.Trace(err)
 		}