ARM: pxa: convert incorrect IRQ_TO_IRQ() to irq_to_gpio()

This fixes the failure to register the IRQ_RTCAlrm alarm as a wakeup
event.  It is misinterpreted as a gpio irq not a PWER bitmask. Fixed
this by converting the incorrect IRQ_TO_IRQ() to a correct version of
irq_to_gpio().

Reported-by: Nick Bane <nickbane1@gmail.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
diff --git a/arch/arm/mach-pxa/pxa25x.c b/arch/arm/mach-pxa/pxa25x.c
index 6bde595..a4af8c5 100644
--- a/arch/arm/mach-pxa/pxa25x.c
+++ b/arch/arm/mach-pxa/pxa25x.c
@@ -285,7 +285,7 @@
 
 static int pxa25x_set_wake(struct irq_data *d, unsigned int on)
 {
-	int gpio = IRQ_TO_GPIO(d->irq);
+	int gpio = irq_to_gpio(d->irq);
 	uint32_t mask = 0;
 
 	if (gpio >= 0 && gpio < 85)