gpio: stmpe: Convert to immutable irq_chip

Convert the driver to immutable irq-chip with a bit of
intuition.

Cc: Marc Zyngier <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Reviewed-by: Marc Zyngier <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-stmpe.c

···
 	int mask = BIT(offset % 8);
 
 	stmpe_gpio->regs[REG_IE][regoffset] &= ~mask;
+	gpiochip_disable_irq(gc, offset);
 }
 
 static void stmpe_gpio_irq_unmask(struct irq_data *d)
···
 	int regoffset = offset / 8;
 	int mask = BIT(offset % 8);
 
+	gpiochip_enable_irq(gc, offset);
 	stmpe_gpio->regs[REG_IE][regoffset] |= mask;
 }
 
···
 	}
 }
 
-static struct irq_chip stmpe_gpio_irq_chip = {
+static const struct irq_chip stmpe_gpio_irq_chip = {
 	.name			= "stmpe-gpio",
 	.irq_bus_lock		= stmpe_gpio_irq_lock,
 	.irq_bus_sync_unlock	= stmpe_gpio_irq_sync_unlock,
 	.irq_mask		= stmpe_gpio_irq_mask,
 	.irq_unmask		= stmpe_gpio_irq_unmask,
 	.irq_set_type		= stmpe_gpio_irq_set_type,
+	.flags			= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
 #define MAX_GPIOS 24
···
 		}
 
 		girq = &stmpe_gpio->chip.irq;
-		girq->chip = &stmpe_gpio_irq_chip;
+		gpio_irq_chip_set_chip(girq, &stmpe_gpio_irq_chip);
 		/* This will let us handle the parent IRQ in the driver */
 		girq->parent_handler = NULL;
 		girq->num_parents = 0;