qemu: migration: Remove TODO about implementing NBD for TUNNELLED migration
qemu: migration: Remove TODO about implementing NBD for TUNNELLED migration

Our streams are not the best transport for migration data and we support
TLS for security now. It's unlikely that there will be enough motivation
to add a new migration protocol to tunnel NBD too.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

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