qemu: cold-plug of sound
qemu: cold-plug of sound

With this patch users can cold plug some sound devices.
use "virsh attach-device vm sound.xml --config" command.
Consider the following sound.xml for a domain:
    <sound model='ich6'>
         <address type='pci' domain='0x0000' bus='0x00' slot='xxx' function='0'/>
    </sound>

Reviewed-by: Cole Robinson <7cd45ff6ad1fb7cf556a02797d774247851499f8@redhat.com>
Signed-off-by: Jidong Xia <feb126af04648bdd581f9c614202ddcea95d5e27@cmss.chinamobile.com>

nertpinx/libvirt,nertpinx/libvirt,zippy2/libvirt,jardasgit/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jardasgit/libvirt,olafhering/libvirt,zippy2/libvirt,crobinso/libvirt,nertpinx/libvirt,libvirt/libvirt,jardasgit/libvirt,jardasgit/libvirt,zippy2/libvirt,jfehlig/libvirt,libvirt/libvirt,jardasgit/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,zippy2/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,crobinso/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,olafhering/libvirt