MIPS: ATH79: Add irq chip ar7240-misc-intc

MIPS: ATH79: Add irq chip ar7240-misc-intc

The ar7240 misc irq chip use ack handler
instead of ack_mask handler. All new ath79 chips use
the ar7240 misc irq chip

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Acked-by: Alban Bedel <albeu@free.fr>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: devicetree@vger.kernel.org
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>