x86-32, NUMA: implement temporary NUMA init shims

To help transition to common NUMA init, implement temporary 32bit
shims for numa_add_memblk() and numa_set_distance().
numa_add_memblk() registers the memblk and adjusts
node_start/end_pfn[].  numa_set_distance() is noop.

These shims will allow using 64bit NUMA init functions on 32bit and
gradual transition to common NUMA init path.

For detailed description, please read description of commits which
make use of the shim functions.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>