Include proper header file for PFN_DOWN()

The recent commit (99a10a60ba9bedcf5d70ef81414d3e03816afa3f) to fix up
mmap_kmem() broke compiles because it used PFN_DOWN() without including
<linux/pfn.h>.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 file changed