net: dsa: qca8k: move regmap init in probe and set it mandatory

In preparation for regmap conversion, move regmap init in the probe
function and make it mandatory as any read/write/rmw operation will be
converted to regmap API.
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/qca8k.c

@@ -1086,12 +1086,6 @@ qca8k_setup(struct dsa_switch *ds)
 	if (ret)
 		return ret;
 
-	/* Start by setting up the register mapping */
-	priv->regmap = devm_regmap_init(ds->dev, NULL, priv,
-					&qca8k_regmap_config);
-	if (IS_ERR(priv->regmap))
-		dev_warn(priv->dev, "regmap initialization failed");
-
 	ret = qca8k_setup_mdio_bus(priv);
 	if (ret)
 		return ret;
@@ -2073,6 +2067,14 @@ qca8k_sw_probe(struct mdio_device *mdiodev)
 		gpiod_set_value_cansleep(priv->reset_gpio, 0);
 	}
 
+	/* Start by setting up the register mapping */
+	priv->regmap = devm_regmap_init(&mdiodev->dev, NULL, priv,
+					&qca8k_regmap_config);
+	if (IS_ERR(priv->regmap)) {
+		dev_err(priv->dev, "regmap initialization failed");
+		return PTR_ERR(priv->regmap);
+	}
+
 	/* Check the detected switch id */
 	ret = qca8k_read_switch_id(priv);
 	if (ret)