Synology: Fix driver to be compatible with python3
Synology: Fix driver to be compatible with python3

Fix the type error between str and byte of AES and
RSA cipher functions

Change-Id: I8a28f8753c8a29950f704391c8956f701685b331
Closes-bug: #1841574

mahak/cinder,mahak/cinder,openstack/cinder,openstack/cinder