Description of problem:
Failed to delete shutoff vm if  'firmware=efi' to uefi guest xml via virt-manager 

Version-Release number of selected component (if applicable):
virt-manager-2.2.1-3.el8.noarch
virt-install-2.2.1-3.el8.noarch
qemu-kvm-4.2.0-32.module+el8.3.0+7629+c86ce105.x86_64
libvirt-6.0.0-27.module+el8.3.0+7602+4b93512e.x86_64


How reproducible:
100%

Steps to Reproduce:
1. Prepare a uefi vm with below xml and firmware shows 'UEFI x86_64: /usr/share/edk2/ovmf/OVMF_CODE.secboot.fd' in virt-manager
# virsh dumpxml rhel8.2-efi
....
  <os>
    <type arch="x86_64" machine="pc-q35-rhel8.2.0">hvm</type>
    <loader readonly="yes" secure="yes" type="pflash">/usr/share/edk2/ovmf/OVMF_CODE.secboot.fd</loader>
    <nvram>/var/lib/libvirt/qemu/nvram/rhel8.2-efi_VARS.fd</nvram>
    <boot dev="hd"/>
  </os>
....

2. Power off vm and add "firmware='efi'" to vm's xml, check vm xml file
 
# virsh dumpxml rhel8.2-efi --inactive |grep firmware -A 5

  <os firmware="efi">
    <type arch="x86_64" machine="pc-q35-rhel8.2.0">hvm</type>
    <boot dev="hd"/>
  </os>

3. Power on vm to ensure the vm can boot up successfully.
Result: vm can start successfully

4. Power off vm again and delete it via virt-manager

Error deleting virtual machine 'rhel8.2-efi': Requested operation is not valid: cannot undefine domain with nvram

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/object/domain.py", line 1303, in delete
    self._backend.undefineFlags(flags)
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 2924, in undefineFlags
    if ret == -1: raise libvirtError ('virDomainUndefineFlags() failed', dom=self)
libvirt.libvirtError: Requested operation is not valid: cannot undefine domain with nvram

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/delete.py", line 191, in _async_delete
    vm.delete()
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 66, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/domain.py", line 1307, in delete
    self._backend.undefine()
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 2888, in undefine
    if ret == -1: raise libvirtError ('virDomainUndefine() failed', dom=self)
libvirt.libvirtError: Requested operation is not valid: cannot undefine domain with nvram


Additionally, there were errors removing certain storage devices: 


Actual results:
As described.

Expected results:
Fix it.

Additional info:
The VM can be deleted by # virsh undefine $vm --nvram command, thanks.