ACPI: irq: Introduce acpi_get_gsi_dispatcher()

ACPI: irq: Introduce acpi_get_gsi_dispatcher()

Using acpi_irq_create_hierarchy() in the cases where the code
also handles OF leads to code duplication as the ACPI subsystem
doesn't provide means to compute the IRQ domain parent whereas
the OF does.

Introduce acpi_get_gsi_dispatcher() so that the drivers relying
on both ACPI and OF may use irq_domain_create_hierarchy() in the
common code paths.

No functional changes.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20250428210742.435282-11-romank@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250428210742.435282-11-romank@linux.microsoft.com>