powerpc: Fix build error with 64K pages and !hugetlbfs

HAVE_ARCH_UNMAPPED_AREA and HAVE_ARCH_UNMAPPED_AREA_TOPDOWN must
be defined whenever CONFIG_PPC_MM_SLICES is enabled, not just when
CONFIG_HUGETLB_PAGE is.  They used to be always defined together but
this is no longer the case since 3a8247cc2c856930f34eafce33f6a039227ee175
("powerpc: Only demote individual slices rather than whole process").

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index db0b8f3..4597c49 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -153,12 +153,10 @@
 #define __S110	PAGE_SHARED_X
 #define __S111	PAGE_SHARED_X
 
-#ifdef CONFIG_HUGETLB_PAGE
-
+#ifdef CONFIG_PPC_MM_SLICES
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
-
-#endif
+#endif /* CONFIG_PPC_MM_SLICES */
 
 #ifndef __ASSEMBLY__