gpio: mxc: Fix disabled interrupt wake-up support

A disabled/masked interrupt marked as wakeup source must be re-enable
and unmasked in order to be able to wake-up the host. That can be done
by flaging the irqchip with IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND.

Note: It 'sometimes' works without that change, but only thanks to the
lazy generic interrupt disabling (keeping interrupt unmasked).

Reported-by: Michal Koziel <michal.koziel@emlogic.no>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Author: Loic Poulain

drivers/gpio/gpio-mxc.c

@@ -334,7 +334,7 @@ static int mxc_gpio_init_gc(struct mxc_gpio_port *port, int irq_base)
 	ct->chip.irq_unmask = irq_gc_mask_set_bit;
 	ct->chip.irq_set_type = gpio_set_irq_type;
 	ct->chip.irq_set_wake = gpio_set_wake_irq;
-	ct->chip.flags = IRQCHIP_MASK_ON_SUSPEND;
+	ct->chip.flags = IRQCHIP_MASK_ON_SUSPEND | IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND;
 	ct->regs.ack = GPIO_ISR;
 	ct->regs.mask = GPIO_IMR;