irqchip/gic-v5: Split IRS probing into OF and generic portions

irqchip/gic-v5: Split IRS probing into OF and generic portions

Split the IRS driver code into OF specific and generic portions in order
to pave the way for adding ACPI firmware bindings support.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Acked-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260115-gicv5-host-acpi-v3-3-c13a9a150388@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>