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 <damm@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-em.c

@@ -338,7 +338,7 @@ static int em_gio_probe(struct platform_device *pdev)
 	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,