powerpc/mm: Abstraction for vmemmap and map_kernel_page()

For hash we create vmemmap mapping using bolted hash page table entries.
For radix we fill the radix page table. The next patch will add the
radix details for creating vmemmap mappings.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/init_64.c

@@ -240,9 +240,6 @@ static __meminit void vmemmap_list_populate(unsigned long phys,
 	vmemmap_list = vmem_back;
 }
 
-extern int __meminit vmemmap_create_mapping(unsigned long start,
-					    unsigned long page_size,
-					    unsigned long phys);
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 {
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
@@ -281,8 +278,6 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-extern void vmemmap_remove_mapping(unsigned long start,
-				   unsigned long page_size);
 static unsigned long vmemmap_list_free(unsigned long start)
 {
 	struct vmemmap_backing *vmem_back, *vmem_back_prev;