When EFI memory map is traversed to determine the extents of each node, the
minimal and maximal PFNs are stored in the bootmem_data structures. The
same information ls later stored in the mem_data array of 'struct
early_node_data'.

Switch to using mem_data from the very beginning.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>