MIPS: Pistachio: Enable KASLR

Allow KASLR to be selected on Pistachio based systems. Tested on a
Creator Ci40.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Jonas Gorski <jogo@openwrt.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13356/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>