genirq: Add prototype for handle_nested_irq()

The function is supposed to be called from the primary IRQ
handler for a demultiplexing chip so make a protype visible for
them.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
LKML-Reference: <1251142084-9852-1-git-send-email-broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/irq.h

@@ -282,6 +282,7 @@ extern void handle_edge_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_simple_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_percpu_irq(unsigned int irq, struct irq_desc *desc);
 extern void handle_bad_irq(unsigned int irq, struct irq_desc *desc);
+extern void handle_nested_irq(unsigned int irq);
 
 /*
  * Monolithic do_IRQ implementation.