imported the restart_waiter from swsssommon

Author: kanza-latif

scripts/hostcfgd

@@ -18,6 +18,7 @@ from sonic_py_common import device_info
 from sonic_py_common.general import check_output_pipe
 from swsscommon.swsscommon import ConfigDBConnector, DBConnector, Table
 import swsscommon
+from swsscommon.common/restart_waiter import RestartWaiter
 from sonic_installer import bootloader
 hostcfg_file_path = os.path.abspath(__file__)
 hostcfg_dir_path = os.path.dirname(hostcfg_file_path)