[PATCH] mm: fix prototype warning from kernel test robot

[Baoquan He <bhe@redhat.com>]

Kernel test robot calling make with 'W=1' triggering warning like below
below for memmap_init_zone() function.

mm/page_alloc.c:6259:23: warning: no previous prototype for 'memmap_init_zone' [-Wmissing-prototypes]
 6259 | void __meminit __weak memmap_init_zone(unsigned long size, int nid,
      |                       ^~~~~~~~~~~~~~~~

Fix it by adding the function declaration in include/linux/mm.h.
Since memmap_init_zone() has a generic version with '__weak',
the declaratoin in ia64 header file can be simply removed.

Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
---
 arch/ia64/include/asm/pgtable.h | 5 -----
 include/linux/mm.h              | 1 +
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index 2c81394a2430..9b4efe89e62d 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -517,11 +517,6 @@ extern struct page *zero_page_memmap_ptr;
 	__changed;							\
 })
 #endif
-
-#  ifdef CONFIG_VIRTUAL_MEM_MAP
-  /* arch mem_map init routine is needed due to holes in a virtual mem_map */
-    extern void memmap_init_zone(struct zone *zone);
-#  endif /* CONFIG_VIRTUAL_MEM_MAP */
 # endif /* !__ASSEMBLY__ */
 
 /*
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 56bb239f9150..073049bd0b29 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2401,6 +2401,7 @@ extern void set_dma_reserve(unsigned long new_dma_reserve);
 extern void memmap_init_range(unsigned long, int, unsigned long,
 		unsigned long, unsigned long, enum meminit_context,
 		struct vmem_altmap *, int migratetype);
+extern void memmap_init_zone(struct zone *zone);
 extern void setup_per_zone_wmarks(void);
 extern int __meminit init_per_zone_wmark_min(void);
 extern void mem_init(void);
-- 
2.17.2