gpiolib: wm8994: Use irq_domain mappings for gpios

This has no practical impact at present since we don't support device tree
so any user must have set an irq_base but this will in future allow a
transition to device tree with minimal invasiveness.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-wm8994.c

@@ -19,6 +19,7 @@
 #include <linux/mfd/core.h>
 #include <linux/platform_device.h>
 #include <linux/seq_file.h>
+#include <linux/regmap.h>
 
 #include <linux/mfd/wm8994/core.h>
 #include <linux/mfd/wm8994/pdata.h>
@@ -109,10 +110,7 @@ static int wm8994_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
 	struct wm8994_gpio *wm8994_gpio = to_wm8994_gpio(chip);
 	struct wm8994 *wm8994 = wm8994_gpio->wm8994;
 
-	if (!wm8994->irq_base)
-		return -EINVAL;
-
-	return wm8994->irq_base + offset;
+	return regmap_irq_get_virq(wm8994->irq_data, offset);
 }