mm/mm_init.c: don't initialize page->lru again

mm/mm_init.c: don't initialize page->lru again

Current page initialization call flow looks like this with some
simplification:

setup_arch()
  paging_init()
    free_area_init()
      memmap_init()
        memmap_init_zone_range()
	  memmap_init_range()
	    defer_init()
	    __init_single_page()
mm_core_init()
  mem_init()
    memblock_free_all()
      free_low_memory_core_early()
        memmap_init_reserved_pages()
          reserve_bootmem_region()
	    init_reserved_page()
	      __init_single_page()

There two cases depends on CONFIG_DEFERRED_STRUCT_PAGE_INIT.

  * If CONFIG_DEFERRED_STRUCT_PAGE_INIT, pages after first_init_pfn is
    skipped at defer_init(). Then init_reserved_page() is defined to
    call __init_single_page() for them.
  * If !CONFIG_DEFERRED_STRUCT_PAGE_INIT, pages are all initialized by
    memmap_init_range().

In both cases, after init_reserved_page(), we expect __init_single_page()
has done its work to the page, which already initialize page->lru properly.

We don't need to do it again.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Link: https://lore.kernel.org/r/20240610143742.26401-1-richard.weiyang@gmail.com
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>