x86_64: fix section mismatch warning in init.c

Fix following warning:
WARNING: vmlinux.o(.text+0x188ea): Section mismatch: reference to .init.text:__alloc_bootmem_core (between 'alloc_bootmem_high_node' and 'get_gate_vma')

alloc_bootmem_high_node() is only used from __init scope so declare it __init.
And in addition declare the weak variant __init too.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86_64/mm/init.c

@@ -724,7 +724,7 @@ int in_gate_area_no_task(unsigned long addr)
 	return (addr >= VSYSCALL_START) && (addr < VSYSCALL_END);
 }
 
-void *alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size)
+void * __init alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size)
 {
 	return __alloc_bootmem_core(pgdat->bdata, size,
 			SMP_CACHE_BYTES, (4UL*1024*1024*1024), 0);

mm/sparse.c

@@ -209,7 +209,7 @@ static int __meminit sparse_init_one_section(struct mem_section *ms,
 	return 1;
 }
 
-__attribute__((weak))
+__attribute__((weak)) __init
 void *alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size)
 {
 	return NULL;