Xen: fix typo in previous patch

Correctly name the irq_chip structure to fix an immediate failure when booting
as a xen pv_ops guest with a NULL pointer exception. The missing 'x' was
introduced in commit [fb412a17] applied to
2.6.3[25]-stable trees.  The commit to mainline was
[aaca4964] which did not have the problem.
Signed-off-by: James Dingwall <james@dingwall.me.uk>
Reported-by: Pawel Zuzelski <pawelz@pld-linux.org>
Tested-by: Pawel Zuzelski <pawelz@pld-linux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/xen/events.c

@@ -930,7 +930,7 @@ static struct irq_chip xen_dynamic_chip __read_mostly = {
 	.retrigger	= retrigger_dynirq,
 };
 
-static struct irq_chip en_percpu_chip __read_mostly = {
+static struct irq_chip xen_percpu_chip __read_mostly = {
 	.name		= "xen-percpu",
 
 	.disable	= disable_dynirq,