Symptom:
MPEG Source WUI: New Device Type names are getting deleted

Conditions:
Issue recreation steps:
1. Goto EC>Network Element Provisioning>MPEG Source
2. Add a new MPEG Source by clicking the [Add] button.
3. In the Device Type field, choose "New Device Type"
4. Enter the new device name.
5. Complete all the remaining fields and Save.
6. New MPEG Source will get listed in the MPEG source list.
7. Select the newly added MPEG Source and delete it.
8. Click [Add] and click on  Device Type field and observe the names listed in it.

Expected result:
 Newly added device name shouldn't be deleted from the Device type field while deleting the corresponding MPEG Source