Current mmconfig has some problems of remapped range.

a) In the case of broken MCFG tables on Asus etc., we need to remap 256M
   range, but currently only remap 1M.

b) The base address always corresponds to bus number 0, but currently we
   are assuming it corresponds to start bus number.

This patch fixes the above problems.

(akpm: Arjan suggests that if the MCFG table is broken we just shouldn't use
it, rather than try to work around things).
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>