powerpc/crashdump: Do not fail on NULL pointer dereferencing

commit 426b6cb4 upstream.
Signed-off-by: Maxim Uvarov <muvarov@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Kamalesh babulal <kamalesh@linux.vnet.ibm.com>
cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/powerpc/kernel/crash.c

@@ -377,6 +377,9 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
 	for_each_irq(i) {
 		struct irq_desc *desc = irq_desc + i;
 
+		if (!desc || !desc->chip || !desc->chip->eoi)
+			continue;
+
 		if (desc->status & IRQ_INPROGRESS)
 			desc->chip->eoi(i);