pinctrl: microchip-sgpio: make irq_chip immutable

Since recently, the kernel is nagging about mutable irq_chips:

[    4.967050] gpio gpiochip1: (e2004190.gpio-input): not an immutable chip, please consider fixing it!

Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
helper functions and call the appropriate gpiolib functions.
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220428111622.1395831-1-michael@walle.ccSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-microchip-sgpio.c

@@ -688,11 +688,17 @@ static void microchip_sgpio_irq_setreg(struct irq_data *data,
 
 static void microchip_sgpio_irq_mask(struct irq_data *data)
 {
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+
 	microchip_sgpio_irq_setreg(data, REG_INT_ENABLE, true);
+	gpiochip_disable_irq(chip, data->hwirq);
 }
 
 static void microchip_sgpio_irq_unmask(struct irq_data *data)
 {
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
+
+	gpiochip_enable_irq(chip, data->hwirq);
 	microchip_sgpio_irq_setreg(data, REG_INT_ENABLE, false);
 }
 
@@ -746,6 +752,8 @@ static const struct irq_chip microchip_sgpio_irqchip = {
 	.irq_ack	= microchip_sgpio_irq_ack,
 	.irq_unmask	= microchip_sgpio_irq_unmask,
 	.irq_set_type	= microchip_sgpio_irq_set_type,
+	.flags		= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
 static void sgpio_irq_handler(struct irq_desc *desc)
@@ -861,11 +869,7 @@ static int microchip_sgpio_register_bank(struct device *dev,
 		if (irq) {
 			struct gpio_irq_chip *girq = &gc->irq;
 
-			girq->chip = devm_kmemdup(dev, &microchip_sgpio_irqchip,
-						  sizeof(microchip_sgpio_irqchip),
-						  GFP_KERNEL);
-			if (!girq->chip)
-				return -ENOMEM;
+			gpio_irq_chip_set_chip(girq, &microchip_sgpio_irqchip);
 			girq->parent_handler = sgpio_irq_handler;
 			girq->num_parents = 1;
 			girq->parents = devm_kcalloc(dev, 1,