MIPS: Malta: Use syscon-reboot driver to reboot

Make use of the generic syscon-reboot driver to reboot the Malta board,
reducing the amount of platform code it requires.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Stephan Linz <linz@li-pro.net>
Cc: Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14279/


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