genirq: Irqchip: document gcflags arg of irq_alloc_domain_generic_chips

Commit 088f40b7 ("genirq: Generic chip:
Add linear irq domain support") missed kerneldoc for the gcflags
argument of irq_alloc_domain_generic_chips(). Add it now.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Link: http://lkml.kernel.org/r/1371564513-4327-1-git-send-email-james.hogan@imgtec.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/irq/generic-chip.c

@@ -254,6 +254,7 @@ irq_gc_init_mask_cache(struct irq_chip_generic *gc, enum irq_gc_flags flags)
  * @handler:		Default flow handler associated with these chips
  * @clr:		IRQ_* bits to clear in the mapping function
  * @set:		IRQ_* bits to set in the mapping function
+ * @gcflags:		Generic chip specific setup flags
  */
 int irq_alloc_domain_generic_chips(struct irq_domain *d, int irqs_per_chip,
 				   int num_ct, const char *name,