[PATCH] ppc64: four level pagetables fix

With CONFIG_HUGETLB_PAGE=n:

In file included from kernel/sysctl.c:37:
include/linux/hugetlb.h:104:1: warning: "hugetlb_free_pgd_range" redefined
In file included from include/linux/mm.h:36,
                 from kernel/sysctl.c:23:
include/asm/pgtable.h:492:1: warning: this is the location of the previous definition

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>