drivers/rtc/rtc-pcf8563.c: fix pcf8563_irq() error return value

As pointed out by Sergei Shtylyov, the pcf8563_irq function contains a
bug in the error handling: an interrupt handler is not supposed to
return an errno value but an 'enum irqreturn'.

Let's fix this by returning IRQ_NONE in case of a communication error.

Signed-off-by: Arnd Bergmann <[e-mail]>
Cc: Sergei Shtylyov <[e-mail]>
Cc: Alessandro Zummo <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/rtc/rtc-pcf8563.c

···
 
 	err = pcf8563_get_alarm_mode(pcf8563->client, NULL, &pending);
 	if (err)
-		return err;
+		return IRQ_NONE;
 
 	if (pending) {
 		rtc_update_irq(pcf8563->rtc, 1, RTC_IRQF | RTC_AF);