xen: Use the proper irq functions

generic_handler_irq() already tests for !desc so use this instead of
generic_handle_irq_desc().

Use irq_get_irq_data() instead of desc->irq_data.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Xen <xen-devel@lists.xenproject.org>
Link: http://lkml.kernel.org/r/20140223212738.222412125@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index 1de2a19..96109a9 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -235,14 +235,10 @@
 static void handle_irq_for_port(unsigned port)
 {
 	int irq;
-	struct irq_desc *desc;
 
 	irq = get_evtchn_to_irq(port);
-	if (irq != -1) {
-		desc = irq_to_desc(irq);
-		if (desc)
-			generic_handle_irq_desc(irq, desc);
-	}
+	if (irq != -1)
+		generic_handle_irq(irq);
 }
 
 static void consume_one_event(unsigned cpu,