irq: Add a method to convert an interrupt to ACPI

When generating ACPI tables we need to convert IRQs in U-Boot to the ACPI
structures required by ACPI. This is a SoC-specific conversion and cannot
be handled by generic code, so add a new IRQ method to do the conversion.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
5 files changed