MIPS: Malta: initialise MAARs

Initialise the MAARs such that speculation is enabled for all physical
addresses outside of the I/O region.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7333/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>