[PATCH] Sparsemem build fix

From: Ralf Baechle <ralf@linux-mips.org>

<linux/mmzone.h> uses PAGE_SIZE, PAGE_SHIFT from <asm/page.h> without
including that header itself.  For some sparsemem configurations this may
result in build errors like:

  CC      init/initramfs.o
In file included from include/linux/gfp.h:4,
                 from include/linux/slab.h:15,
                 from include/linux/percpu.h:4,
                 from include/linux/rcupdate.h:41,
                 from include/linux/dcache.h:10,
                 from include/linux/fs.h:226,
                 from init/initramfs.c:2:
include/linux/mmzone.h:498:22: warning: "PAGE_SHIFT" is not defined
In file included from include/linux/gfp.h:4,
                 from include/linux/slab.h:15,
                 from include/linux/percpu.h:4,
                 from include/linux/rcupdate.h:41,
                 from include/linux/dcache.h:10,
                 from include/linux/fs.h:226,
                 from init/initramfs.c:2:
include/linux/mmzone.h:526: error: `PAGE_SIZE' undeclared here (not in a function)
include/linux/mmzone.h: In function `__pfn_to_section':
include/linux/mmzone.h:573: error: `PAGE_SHIFT' undeclared (first use in this function)
include/linux/mmzone.h:573: error: (Each undeclared identifier is reported only once
include/linux/mmzone.h:573: error: for each function it appears in.)
include/linux/mmzone.h: In function `pfn_valid':
include/linux/mmzone.h:578: error: `PAGE_SHIFT' undeclared (first use in this function)
make[1]: *** [init/initramfs.o] Error 1
make: *** [init] Error 2

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Seems-reasonable-to: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>