We currently need this either to allocate the next ram_addr_t for a
new block, or for total memory to be migrated.  Both of which we can
calculate without need of this to keep us in a contiguous address space.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>