Fixed Wrong InterfaceStack for QinQ VLAN (double vlan) interface
Based on the network interface stack , when we have set higher layer as "VLANTermination" interface and then go on setting lower layer . It directly sets it to "Device.Ethernet.Link.{i}" as previously the code did not have the option of setting it to "VLANTermination" (Required for QinQ VLAN creation).
With this fix , one more if case is introduced to facilitate the option of selecting lower layer as "VLANTermination" interface before setting it directly to "Device.Ethernet.Link.{i}".