ARM: cns3xxx: fix mapping of private memory region

Since commit 0536bdf3

 (ARM: move iotable mappings within the vmalloc
region), the Cavium CNS3xxx cannot boot anymore.

This is caused by the pre-defined iotable mappings is not in the vmalloc
region. This patch move the iotable mappings into the vmalloc region, and
merge the MPCore private memory region (containing the SCU, the GIC and
the TWD) as a single region.

Signed-off-by: Mac Lin <mkl0301@gmail.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>
Cc: stable@vger.kernel.org [v3.3+]