Convert to sparsemem and remove all the discontigmem code in the
process. This has a few advantages:

- The old numa_memory_lookup_table can go away
- All the arch specific discontigmem magic can go away

We also remove the triple pass of memory properties and instead create a
list of per node extents that we iterate through. A final cleanup would
be to change our lmb code to store extents per node, then we can reuse
that information in the numa code.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>