Indicates how many pages we are going to send in each batch to a multifd
thread.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NPeter Xu <peterx@redhat.com>

--

Be consistent with defaults and documentation
Use new DEFINE_PROP_*
Rename x-multifd-group to x-multifd-page-count