irqchip/gic-pm: Fix suspend handling

If interrupts are enabled for a non-root GIC device that uses the
gic-pm driver, when system suspend occurs, the current interrupt
state is not saved and restored correctly and so interrupts do not
work again on resuming the system. Add a late suspend handler to
save and restore the state for these devices.

Suggested-by: Jonathan Hunter <jonathanh@nvidia.com>
Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-pm.c

@@ -142,6 +142,8 @@ irq_dispose:
 static const struct dev_pm_ops gic_pm_ops = {
 	SET_RUNTIME_PM_OPS(gic_runtime_suspend,
 			   gic_runtime_resume, NULL)
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				     pm_runtime_force_resume)
 };
 
 static const char * const gic400_clocks[] = {