Introduce ACPI_IRQ_MODEL_GIC which is needed for ARM64 as GIC is
used, and then register device's gsi with the core IRQ subsystem.

acpi_register_gsi() is similar to DT based irq_of_parse_and_map(),
since gsi is unique in the system, so use hwirq number directly
for the mapping.

We are going to implement stacked domains when GICv2m, GICv3, ITS
support are added.

CC: Marc Zyngier <marc.zyngier@arm.com>
Originally-by: NAmit Daniel Kachhap <amit.daniel@samsung.com>
Tested-by: NSuravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: NYijing Wang <wangyijing@huawei.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NJon Masters <jcm@redhat.com>
Tested-by: NTimur Tabi <timur@codeaurora.org>
Tested-by: NRobert Richter <rrichter@cavium.com>
Acked-by: NRobert Richter <rrichter@cavium.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>