Patch from Lothar Wassmann

Hi,
ioremapping a memory range that ends on the first byte of a page
(e.g. mapping PAGE_SIZE + 1 bytes on a page boundary) results in a
mapping that is one page too short. In particular trying to create a 1
byte mapping at the start of a page results in a BUG_ON() assertion in
remap_area_pages() because the calculated mapping size is zero.
This bug has been reported on Bugzilla on 2004-02-25:
http://bugzilla.kernel.org/show_bug.cgi?id=2188

Signed-off-by: Lothar Wassmann
Signed-off-by: Russell King