Revert "x86_64: allocate sparsemem memmap above 4G"

Revert "x86_64: allocate sparsemem memmap above 4G"

This reverts commit 25938e8faeb6da3142e00dd48c4403b8b0cc4fec.

First off, testing in Fedora has shown it to cause boot failures,
bisected down by Martin Ebourne, and reported by Dave Jobes.  So the
commit will likely be reverted in the 2.6.23 stable kernels.

Secondly, in the 2.6.24 model, x86-64 has now grown support for
SPARSEMEM_VMEMMAP, which disables the relevant code anyway, so while the
bug is not visible any more, it's become invisible due to the code just
being irrelevant and no longer enabled on the only architecture that
this ever affected.

Reported-by: Dave Jones <davej@redhat.com>
Tested-by: Martin Ebourne <fedora@ebourne.me.uk>
Cc: Zou Nan hai <nanhai.zou@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>