powerpc: Fix missing/delayed calls to irq_work

When replaying interrupts (as a result of the interrupt occurring while soft-disabled), in the case of the decrementer, we are exclusively testing for a pending timer target. However we also use decrementer interrupts to trigger the new "irq_work", which in this case would be missed.

This change the logic to force a replay in both cases of a timer boundary reached and a decrementer interrupt having actually occurred while disabled. The former test is still useful to catch cases where a CPU having been hard-disabled for a long time completely misses the interrupt due to a decrementer rollover.

---

index 5cbcf4d..ea185e0 100644
@@ -162,7 +162,7 @@ notrace unsigned int __check_irq_replay(void)
 	 * in case we also had a rollover while hard disabled
 	 */
 	local_paca->irq_happened &= ~PACA_IRQ_DEC;
-	if (decrementer_check_overflow())
+	if ((happened & PACA_IRQ_DEC) || decrementer_check_overflow())
 		return 0x900;
 
 	/* Finally check if an external interrupt happened */