irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch

For LoongArch, ACPI_IRQ_MODEL_LPIC is introduced, and then the
callback acpi_get_gsi_domain_id and acpi_gsi_to_irq_fallback are
implemented.

The acpi_get_gsi_domain_id callback returns related fwnode handle
of irqdomain for different GSI range.

The acpi_gsi_to_irq_fallback will create new mapping for gsi when
the mapping of it is not found.

Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1658314292-35346-14-git-send-email-lvjianmin@loongson.cn