powerpc/mm: Move register_process_table() out of ppc_md

We want to initialise register_process_table() before ppc_md is setup,
so that it can be called as part of MMU init (at least on Radix ATM).

That no longer works because probe_machine() requires that ppc_md be
empty before it's called, and we now do probe_machine() much later.

So make register_process_table a global for now. It will probably move
into a mmu_radix_ops struct at some point in the future.

This was broken by me when applying commit 7025776ed1 "powerpc/mm:
Move hash table ops to a separate structure" due to conflicts with other
patches.

Fixes: 7025776ed1 ("powerpc/mm: Move hash table ops to a separate structure")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/book3s/64/mmu.h

@@ -134,5 +134,9 @@ static inline void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 	return hash__setup_initial_memory_limit(first_memblock_base,
 					   first_memblock_size);
 }
+
+extern int (*register_process_table)(unsigned long base, unsigned long page_size,
+				     unsigned long tbl_size);
+
 #endif /* __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_MMU_H_ */

arch/powerpc/include/asm/machdep.h

@@ -219,8 +219,6 @@ struct machdep_calls {
 #ifdef CONFIG_ARCH_RANDOM
 	int (*get_random_seed)(unsigned long *v);
 #endif
-	int (*register_process_table)(unsigned long base, unsigned long page_size,
-				      unsigned long tbl_size);
 };
 
 extern void e500_idle(void);