gpio: sl28cpld: Replace irqchip mask_invert with unmask_base

Remove use of the deprecated mask_invert flag. Inverted mask
registers (where a '1' bit enables an IRQ) can be described more
directly as an unmask register.
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-sl28cpld.c

@@ -70,8 +70,7 @@ static int sl28cpld_gpio_irq_init(struct platform_device *pdev,
 	irq_chip->num_irqs = ARRAY_SIZE(sl28cpld_gpio_irqs);
 	irq_chip->num_regs = 1;
 	irq_chip->status_base = base + GPIO_REG_IP;
-	irq_chip->mask_base = base + GPIO_REG_IE;
-	irq_chip->mask_invert = true;
+	irq_chip->unmask_base = base + GPIO_REG_IE;
 	irq_chip->ack_base = base + GPIO_REG_IP;
 
 	ret = devm_regmap_add_irq_chip_fwnode(dev, dev_fwnode(dev),