x86/pci: Add cap_resource()

Prepare for 32bit pci root bus

-v2: hpa said we should compare with (resource_size_t)~0
-v3: according to Linus to use MAX_RESOURCE instead.
     also need need to put related patches together
-v4: according to Andrew, use min in cap_resource()

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1265793639-15071-8-git-send-email-yinghai@kernel.org>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>