<pre>
Foreman: develop
Libvirt: 7.6.0
OS: Fedora 35
qemu-kvm: 6.1.0 (qemu-6.1.0-15.fc35)
</pre>

**Steps to reproduce**
* Try to create host with libvirt CR

**Error:**
<pre>
Failed to power up a compute L7.6.0 (Libvirt) instance jesse-kimmins.kokos.loc: C
all to virDomainCreateWithFlags failed: Cannot get interface MTU on '': No such device
ESC[32m2022-07-04T14:33:04ESC[0m [ESC[32mIESC[0m|ESC[36mappESC[0m|3da41144] Backtrace for 'Failed to power up a compute L7.6.0 (Libvirt) instance jesse-kimmi
ns.kokos.loc: Call to virDomainCreateWithFlags failed: Cannot get interface MTU on '': No such device' error (Libvirt::Error): Call to virDomainCreateWithFla
gs failed: Cannot get interface MTU on '': No such device
 3da41144 | /home/projects/foreman/.bundle/ruby/2.7.0/gems/fog-libvirt-0.9.0/lib/fog/libvirt/requests/compute/vm_action.rb:7:in `create'
 3da41144 | /home/projects/foreman/.bundle/ruby/2.7.0/gems/fog-libvirt-0.9.0/lib/fog/libvirt/requests/compute/vm_action.rb:7:in `vm_action'
 3da41144 | /home/projects/foreman/.bundle/ruby/2.7.0/gems/fog-libvirt-0.9.0/lib/fog/libvirt/models/compute/server.rb:76:in `start'
 3da41144 | /home/projects/foreman/app/models/compute_resource.rb:187:in `start_vm'
 3da41144 | /home/projects/foreman/app/models/concerns/orchestration/compute.rb:229:in `setComputePowerUp'
 3da41144 | /home/projects/foreman/app/models/concerns/orchestration.rb:227:in `execute'
 3da41144 | /home/projects/foreman/app/models/concerns/orchestration.rb:152:in `block in process'
 3da41144 | /home/projects/foreman/app/models/concerns/orchestration.rb:144:in `each'
 3da41144 | /home/projects/foreman/app/models/concerns/orchestration.rb:144:in `process'
 3da41144 | /home/projects/foreman/app/models/concerns/orchestration.rb:44:in `around_save_orchestration'
</pre>