mm, tile: drop arch_{add,remove}_memory

these functions are unreachable because tile doesn't support memory
hotplug becasuse it doesn't select ARCH_ENABLE_MEMORY_HOTPLUG nor
it supports SPARSEMEM.

This code hasn't been compiled for a while obviously because nobody has
noticed that __add_pages has a different signature since 2009.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>

arch/tile/mm/init.c

@@ -857,36 +857,6 @@ void __init mem_init(void)
 #endif
 }
 
-/*
- * this is for the non-NUMA, single node SMP system case.
- * Specifically, in the case of x86, we will always add
- * memory to the highmem for now.
- */
-#ifndef CONFIG_NEED_MULTIPLE_NODES
-int arch_add_memory(u64 start, u64 size, bool for_device)
-{
-	struct pglist_data *pgdata = &contig_page_data;
-	struct zone *zone = pgdata->node_zones + MAX_NR_ZONES-1;
-	unsigned long start_pfn = start >> PAGE_SHIFT;
-	unsigned long nr_pages = size >> PAGE_SHIFT;
-
-	return __add_pages(zone, start_pfn, nr_pages);
-}
-
-int remove_memory(u64 start, u64 size)
-{
-	return -EINVAL;
-}
-
-#ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(u64 start, u64 size)
-{
-	/* TODO */
-	return -EBUSY;
-}
-#endif
-#endif
-
 struct kmem_cache *pgd_cache;
 
 void __init pgtable_cache_init(void)