irqchip: gic: Use mask field in GICC_IAR

Bit[9:0] is interrupt ID field in GICC_IAR. Bit[12:10] is CPU ID field,
and others are reserved.

So we should use GICC_IAR_INT_ID_MASK to get interrupt ID. It's not a good way
to use ~0x1c00 (CPU ID field) to get interrupt ID.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Link: https://lkml.kernel.org/r/1399795571-17231-3-git-send-email-haojian.zhuang@linaro.org


Signed-off-by: Jason Cooper <jason@lakedaemon.net>