MIPS: Set page size to 16KB for malta SMP defconfigs

For Malta defconfigs which may run on an SMP configuration without
hardware cache anti-aliasing, a 16KB page size is a safer default.
Most notably at the moment it will avoid cache aliasing issues for
multicore proAptiv systems.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6579/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>