memblock: Make memblock_alloc_[try_]nid() top-down

NUMA aware memblock alloc functions - memblock_alloc_[try_]nid() -
weren't properly top-down because memblock_nid_range() scanned
forward.  This patch reverses memblock_nid_range(), renames it to
memblock_nid_range_rev() and updates related functions to implement
proper top-down allocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1310460395-30913-7-git-send-email-tj@kernel.org


Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>