Description of problem:
libvirt allow set busNr and numa node for a pci-bridge but won't use it

Version-Release number of selected component (if applicable):
libvirt-2.0.0-5.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. prepare a guest have a xml like this:

    <controller type='pci' index='1' model='pci-bridge'>
      <model name='pci-bridge'/>
      <target chassisNr='1' busNr='254'>
        <node>1</node>
      </target>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </controller>
    <controller type='ide' index='0'>

2. start guest:

# virsh start r7-lhuang
Domain r7-lhuang started

3. check qemu cmdline:

# ps aux|grep qemu

-device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x3 

4. check active xml:

# virsh dumpxml r7-lhuang
...
    <controller type='pci' index='1' model='pci-bridge'>
      <model name='pci-bridge'/>
      <target chassisNr='1' busNr='254'>
        <node>1</node>
      </target>
      <alias name='pci.1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </controller>
...


Actual results:
Libvirt still show the numa node and busNr in active guest xml but didn't use it to build qemu cmd line for pci-bridge (this is a negative test case since pci-bridge won't use these element).

Expected results:
maybe report error during start guest ?

Additional info: