gpio: em: Enable mask on suspend

Now when lazy interrupt disable has been enabled in the driver
then extend the code to set IRQCHIP_MASK_ON_SUSPEND which tells
the core that only IRQs marked as wakeups need to stay enabled
during Suspend-to-RAM.

Tested on the KZM9D board with GPIO-keys.

Signed-off-by: Magnus Damm <[e-mail]>
Acked-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-em.c

···
 	irq_chip->irq_mask = em_gio_irq_disable;
 	irq_chip->irq_unmask = em_gio_irq_enable;
 	irq_chip->irq_set_type = em_gio_irq_set_type;
-	irq_chip->flags	= IRQCHIP_SKIP_SET_WAKE;
+	irq_chip->flags	= IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MASK_ON_SUSPEND;
 
 	p->irq_domain = irq_domain_add_simple(pdev->dev.of_node,
 					      pdata->number_of_pins,