Adopt Microblaze to the memblock API changes, to fix this
build failure:

  CC      arch/microblaze/mm/init.o
 arch/microblaze/mm/init.c: In function 'mm_cmdline_setup':
 arch/microblaze/mm/init.c:236: error: 'struct memblock_type' has no member named 'region'
 ...
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: linux-mm@kvack.org
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <4C8B2A9A.1040303@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>