microblaze: tag highmem_setup() with __meminit

With commit a0cd7a7 ("mm: simplify free_highmem_page() and
free_reserved_page()") the kernel test robot complains about a warning:

WARNING: modpost: vmlinux.o(.text.unlikely+0x23ac): Section mismatch in
  reference from the function highmem_setup() to the function
  .meminit.text:memblock_is_reserved()

This has been broken ever since microblaze added highmem support,
because memblock_is_reserved() was already tagged with "__init" back then -
most probably the function always got inlined, so we never stumbled over
it.

We need __meminit because __init_memblock defaults to that without
CONFIG_ARCH_KEEP_MEMBLOCK" and __init_memblock is not used outside memblock
code.

Reported-by: kernel test robot <[email protected]>
Fixes: 2f2f371 ("microblaze: Highmem support")
Cc: Andrew Morton <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Arvind Sankar <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Michal Simek <[email protected]>

Author: davidhildenbrand

arch/microblaze/mm/init.c

@@ -52,7 +52,7 @@ static void __init highmem_init(void)
 	pkmap_page_table = virt_to_kpte(PKMAP_BASE);
 }
 
-static void highmem_setup(void)
+static void __meminit highmem_setup(void)
 {
 	unsigned long pfn;