This type cleanup also fixes the following sparse warning:

  mm/memblock.c:249:49: warning: Using plain integer as NULL pointer
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: patches@linaro.org
Cc: linux-mm@kvack.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>