mm/memblock: call kmemleak only for logically mapped region

On 32bit, memblock_alloc_range_nid can return block of
memory from highmem. Ensure kmemleak is called only for
logically mapped region.

Change-Id: I4491f199437d8401071ba5f98a8b0eedbaf47b00
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>