mm/memblock: add missing include <linux/bootmem.h>

Commit 26f09e9b3a06 ("mm/memblock: add memblock memory allocation apis")
introduced two new function definitions:

  memblock_virt_alloc_try_nid_nopanic()
  memblock_virt_alloc_try_nid()

and commit ea1f5f3712af ("mm: define memblock_virt_alloc_try_nid_raw")
introduced the following function definition:

  memblock_virt_alloc_try_nid_raw()

This commit adds an include of header file <linux/bootmem.h> to provide
the missing function prototypes.  This silences the following gcc warning
(W=1):

  mm/memblock.c:1334:15: warning: no previous prototype for `memblock_virt_alloc_try_nid_raw' [-Wmissing-prototypes]
  mm/memblock.c:1371:15: warning: no previous prototype for `memblock_virt_alloc_try_nid_nopanic' [-Wmissing-prototypes]
  mm/memblock.c:1407:15: warning: no previous prototype for `memblock_virt_alloc_try_nid' [-Wmissing-prototypes]

Also adds #ifdef blockers to prevent compilation failure on mips/ia64
where CONFIG_NO_BOOTMEM=n as could be seen in commit commit 6cc22dc08a24
("revert "mm/memblock: add missing include <linux/bootmem.h>"").

Because Makefile already does:

  obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o

The #ifdef has been simplified from:

  #if defined(CONFIG_HAVE_MEMBLOCK) && defined(CONFIG_NO_BOOTMEM)

to simply:

  #if defined(CONFIG_NO_BOOTMEM)

Link: http://lkml.kernel.org/r/20180626184422.24974-1-malat@debian.org
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Suggested-by: Tony Luck <tony.luck@intel.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memblock.c

@@ -20,6 +20,7 @@
 #include <linux/kmemleak.h>
 #include <linux/seq_file.h>
 #include <linux/memblock.h>
+#include <linux/bootmem.h>
 
 #include <asm/sections.h>
 #include <linux/io.h>
@@ -1225,6 +1226,7 @@ phys_addr_t __init memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, i
 	return memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE);
 }
 
+#if defined(CONFIG_NO_BOOTMEM)
 /**
  * memblock_virt_alloc_internal - allocate boot memory block
  * @size: size of memory block to be allocated in bytes
@@ -1432,6 +1434,7 @@ void * __init memblock_virt_alloc_try_nid(
 	      (u64)max_addr);
 	return NULL;
 }
+#endif
 
 /**
  * __memblock_free_early - free boot memory block