x86: fix RTC_AIE with CONFIG_HPET_EMULATE_RTC

In the current code, RTC_AIE doesn't work if the RTC relies on
CONFIG_HPET_EMULATE_RTC because the code sets the RTC_AIE flag in
hpet_set_rtc_irq_bit().  The interrupt handles does accidentally check
for RTC_PIE and not RTC_AIE when comparing the time which was set in
hpet_set_alarm_time().

I now verified on a test system here that without the patch applied,
the attached test program fails on a system that has HPET with
2.6.24-rc7-default. That's not critical since I guess the problem has
been there for several kernel releases, but as the fix is quite
obvious.

Configuration is CONFIG_RTC=y and CONFIG_HPET_EMULATE_RTC=y.
Signed-off-by: NBernhard Walle <bwalle@suse.de>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/hpet.c

@@ -657,7 +657,7 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
 		hpet_pie_count = 0;
 	}
 
-	if (hpet_rtc_flags & RTC_PIE &&
+	if (hpet_rtc_flags & RTC_AIE &&
 	    (curr_time.tm_sec == hpet_alarm_time.tm_sec) &&
 	    (curr_time.tm_min == hpet_alarm_time.tm_min) &&
 	    (curr_time.tm_hour == hpet_alarm_time.tm_hour))