qemu: hotplug: Fix handling of the 'copy-on-read' layer with blockdev
qemu: hotplug: Fix handling of the 'copy-on-read' layer with blockdev

My original implementation was completely broken because it attempted to
use object-add/del instead of blockdev-add/del.

https://bugzilla.redhat.com/show_bug.cgi?id=1798366

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Reviewed-by: Daniel Henrique Barboza <627b089ad62deae9aaf06ccfa2c9056df28927e0@gmail.com>

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