Move fdt_irq_fn typedef to fdt.h

The device tree code passes the function generate_irq_prop() to MMIO
devices to create the "interrupts" property. The typedef fdt_irq_fn is the
type used to pass the function to the device. It makes more sense for the
typedef to be in fdt.h with the rest of the device tree functions, so move
it there.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210713170631.155595-2-alexandru.elisei@arm.com


Signed-off-by: Will Deacon <will@kernel.org>