irqchip/meson-gpio: support more than 8 channels gpio irq

Current meson gpio irqchip driver only support 8 channels for gpio irq
line, later chips may have more then 8 channels, so need to modify code
to support more.

Signed-off-by: Qianggui Song <qianggui.song@amlogic.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220225055207.1048-3-qianggui.song@amlogic.com