mm/memory-failure: don't export hwpoison_filter() when !CONFIG_HWPOISON_INJECT

When CONFIG_HWPOISON_INJECT is not enabled, there is no user of the
hwpoison_filter() outside memory-failure.  So there is no need to export
it in that case.

Link: https://lkml.kernel.org/r/20240612071835.157004-8-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406070136.hGQwVbsv-lkp@intel.com/
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c

@@ -294,6 +294,7 @@ int hwpoison_filter(struct page *p)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(hwpoison_filter);
 #else
 int hwpoison_filter(struct page *p)
 {
@@ -301,8 +302,6 @@ int hwpoison_filter(struct page *p)
 }
 #endif
 
-EXPORT_SYMBOL_GPL(hwpoison_filter);
-
 /*
  * Kill all processes that have a poisoned page mapped and then isolate
  * the page.