[PATCH] x86_64: Fix off by one in e820_mapped

This allows a valid iommu placed immediately after memory to work, to be
recognized as after the last byte of memory and not overlapping it.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>