powerpc/mm: Fix slice state initialization for Book3E

On Book3E, MMU_NO_CONTEXT != 0, but the slice_mm_new_context()
macro assumes that it is.  This means that the map of the
page sizes for each slice is always initialized to zeroes
(which happens to be 4k pages), rather than to the correct
default base page size value - which might be 64k.

This patch corrects the problem.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/page_64.h

@@ -130,7 +130,7 @@ extern void slice_set_user_psize(struct mm_struct *mm, unsigned int psize);
 extern void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
 				  unsigned long len, unsigned int psize);
 
-#define slice_mm_new_context(mm)	((mm)->context.id == 0)
+#define slice_mm_new_context(mm)	((mm)->context.id == MMU_NO_CONTEXT)
 
 #endif /* __ASSEMBLY__ */
 #else