device property: Add irq_get to fwnode operation

Add irq_get() fwnode operation to implement fwnode_irq_get() through
fwnode operations, moving the code in fwnode_irq_get() to OF and ACPI
frameworks.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>