genirq: Add flags to irq_chip

Looking through irq_chip implementations I noticed that some of them
have special requirements, like setting the type masked and therefor
fiddle in irq_desc->status. Add a flag field, so the core code can
handle it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/irq.h

@@ -253,6 +253,7 @@ static inline bool irqd_is_level_type(struct irq_data *d)
  * @irq_set_wake:	enable/disable power-management wake-on of an IRQ
  * @irq_bus_lock:	function to lock access to slow bus (i2c) chips
  * @irq_bus_sync_unlock:function to sync and unlock slow bus (i2c) chips
+ * @flags:		chip specific flags
  *
  * @release:		release function solely used by UML
  */
@@ -299,6 +300,8 @@ struct irq_chip {
 	void		(*irq_bus_lock)(struct irq_data *data);
 	void		(*irq_bus_sync_unlock)(struct irq_data *data);
 
+	unsigned long	flags;
+
 	/* Currently used only by UML, might disappear one day.*/
 #ifdef CONFIG_IRQ_RELEASE_METHOD
 	void		(*release)(unsigned int irq, void *dev_id);