fix save err when specify a table name

s.New() will clear all search conditions and search value,when I use Table() to set a table name. Then FirstOrCreate() will use struct name as my database table name,so It doesn't work.

main.go

@@ -444,7 +444,7 @@ func (s *DB) Save(value interface{}) *DB {
 	if !scope.PrimaryKeyZero() {
 		newDB := scope.callCallbacks(s.parent.callbacks.updates).db
 		if newDB.Error == nil && newDB.RowsAffected == 0 {
-			return s.New().FirstOrCreate(value)
+			return s.FirstOrCreate(value)
 		}
 		return newDB
 	}