powerpc/crashdump: Do not fail on NULL pointer dereferencing

Signed-off-by: Maxim Uvarov <muvarov@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/crash.c

@@ -375,6 +375,9 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
 	for_each_irq(i) {
 		struct irq_desc *desc = irq_to_desc(i);
 
+		if (!desc || !desc->chip || !desc->chip->eoi)
+			continue;
+
 		if (desc->status & IRQ_INPROGRESS)
 			desc->chip->eoi(i);