irqchip: mtk-sysirq: Get irq number from register resource size

Originally mtk-sysirq hardcoded supported irq number to 224. This
was fine since all SoCs before support the same number of irqs for
intpol.

However MT8173 intpol support 32 more irq pins, changes to get
irq number from register resource size to suppor MT8173 properly.

Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
Signed-off-by: Eddie Huang <eddie.huang@mediatek.com>
Cc: <srv_heupstream@mediatek.com>
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: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Olof  Johansson <olof@lixom.net>
Cc: Robert Richter <rrichter@cavium.com>
Cc: Mark Brown <broonie@linaro.org>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: <marc.zyngier@arm.com>
Cc: <peter.maydell@linaro.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1421054073-43468-3-git-send-email-eddie.huang@mediatek.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>