With the new powerpc architecture we don't seem to be able to disable huge
pages anymore.

    mm/built-in.o(.toc1+0xae0): undefined reference to `HPAGE_SHIFT'
    make: *** [.tmp_vmlinux1] Error 1

We seem to need to define HPAGE_SHIFT to something when HUGETLB_PAGE isn't
defined.  This patch defines it to PAGE_SHIFT when we have no support.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>