[POWERPC] Add ability to 4K kernel to hash in 64K pages

This adds the ability for a kernel compiled with 4K page size
to have special slices containing 64K pages and hash the right type
of hash PTEs.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5226f70..ecd459d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -546,9 +546,15 @@
 	def_bool y
 	depends on NEED_MULTIPLE_NODES
 
+config PPC_HAS_HASH_64K
+	bool
+	depends on PPC64
+	default n
+
 config PPC_64K_PAGES
 	bool "64k page size"
 	depends on PPC64
+	select PPC_HAS_HASH_64K
 	help
 	  This option changes the kernel logical page size to 64k. On machines
 	  without processor support for 64k pages, the kernel will simulate