Description of problem:
"No available boot source" shows while creating VM from existing PVC

Version-Release number of selected component (if applicable):
v4.12.0

How reproducible:
100%

Steps to Reproduce:
1. create a vm from catalog
2. select blank disk
3. edit the disk by using an existing PVC
4. create the VM

Actual results:
"No available boot source" shows

Expected results:
The VM is created without "No available boot source"

Additional info: