powerpc/mm: Introduce early_init_mmu() on 64-bit

This moves some MMU related init code out of setup_64.c into hash_utils_64.c
and calls it early_init_mmu() and early_init_mmu_secondary(). This will
make it easier to plug in a new MMU type.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index c073de4..cbf1543 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -62,6 +62,10 @@
 
 extern unsigned int __start___mmu_ftr_fixup, __stop___mmu_ftr_fixup;
 
+/* MMU initialization (64-bit only fo now) */
+extern void early_init_mmu(void);
+extern void early_init_mmu_secondary(void);
+
 #endif /* !__ASSEMBLY__ */