xen: events: fix error checks in bind_*_to_irqhandler()

Checking 'irq < 0' doesn't work when 'irq' is unsigned.

The assigned bind_evtchn_to_irq() and bind_virq_to_irq()
return int, so using int appears appropriate.

Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 036343b..589f0a5 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -912,8 +912,7 @@
 			      unsigned long irqflags,
 			      const char *devname, void *dev_id)
 {
-	unsigned int irq;
-	int retval;
+	int irq, retval;
 
 	irq = bind_evtchn_to_irq(evtchn);
 	if (irq < 0)
@@ -955,8 +954,7 @@
 			    irq_handler_t handler,
 			    unsigned long irqflags, const char *devname, void *dev_id)
 {
-	unsigned int irq;
-	int retval;
+	int irq, retval;
 
 	irq = bind_virq_to_irq(virq, cpu);
 	if (irq < 0)