qemu: agent: fix array access
qemu: agent: fix array access

My code movement changed the type of ifaces_ret from
virDomainInterfacePtr * to virDomainInterfacePtr **,
but failed to adjust the condition or dereference the
array correctly.

Signed-off-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Fixes: 6ddb1f803ea38d8d709b984fa9539e34318a9dc0
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

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