Collected ioremap fixes

- Call change_page_attr correctly
- Fix a race during iounmap
- Handle mmio holes without mem_map correctly (needed for SRAT patch)
- Some cleanups
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>