adc: meson-saradc: fix regmap_init_mem call

The SARADC driver was merged after the following commit :
commit d35812368a59 ("regmap: change regmap_init_mem() to take ofnode instead udevice")
Thus breaking build, this patch fixes the regmap_init_mem accordingly.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

drivers/adc/meson-saradc.c

@@ -654,7 +654,7 @@ static int meson_saradc_probe(struct udevice *dev)
 	struct meson_saradc_priv *priv = dev_get_priv(dev);
 	int ret;
 
-	ret = regmap_init_mem(dev, &priv->regmap);
+	ret = regmap_init_mem(dev_ofnode(dev), &priv->regmap);
 	if (ret)
 		return ret;