net: designware: Switch back to mdio_alloc()

Use mdio_alloc() again to allocate MDIO bus. This is possible
because all the miiphybb parameters and ops passing is handled in
at bb_miiphy_read()/bb_miiphy_write() level.

This also fixes previously missed bb_miiphy_free() in .remove
callback of this driver. which does not pose a problem anymore.

Fixes: cbb69c2fafcc ("net: designware: Allocate bb_miiphy using bb_miiphy_alloc() and fill in callbacks")
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
diff --git a/drivers/net/designware.c b/drivers/net/designware.c
index 4827811..0f93c25 100644
--- a/drivers/net/designware.c
+++ b/drivers/net/designware.c
@@ -316,17 +316,14 @@
 static int dw_bb_mdio_init(const char *name, struct udevice *dev)
 {
 	struct dw_eth_dev *dwpriv = dev_get_priv(dev);
-	struct bb_miiphy_bus *bb_miiphy = bb_miiphy_alloc();
-	struct mii_dev *bus;
+	struct mii_dev *bus = mdio_alloc();
 	int ret;
 
-	if (!bb_miiphy) {
+	if (!bus) {
 		printf("Failed to allocate MDIO bus\n");
 		return -ENOMEM;
 	}
 
-	bus = &bb_miiphy->mii;
-
 	debug("\n%s: use bitbang mii..\n", dev->name);
 	ret = gpio_request_by_name(dev, "snps,mdc-gpio", 0,
 				   &dwpriv->mdc_gpio,
@@ -855,7 +852,6 @@
 {
 	struct eth_pdata *pdata = dev_get_plat(dev);
 	struct dw_eth_dev *priv = dev_get_priv(dev);
-	bool __maybe_unused bbmiiphy = false;
 	phys_addr_t iobase = pdata->iobase;
 	void *ioaddr;
 	int ret, err;
@@ -947,8 +943,7 @@
 	priv->max_speed = pdata->max_speed;
 
 #if IS_ENABLED(CONFIG_BITBANGMII) && IS_ENABLED(CONFIG_DM_GPIO)
-	bbmiiphy = dev_read_bool(dev, "snps,bitbang-mii");
-	if (bbmiiphy) {
+	if (dev_read_bool(dev, "snps,bitbang-mii")) {
 		ret = dw_bb_mdio_init(dev->name, dev);
 		if (ret) {
 			err = ret;
@@ -978,12 +973,7 @@
 	/* continue here for cleanup if no PHY found */
 	err = ret;
 	mdio_unregister(priv->bus);
-#if IS_ENABLED(CONFIG_BITBANGMII) && IS_ENABLED(CONFIG_DM_GPIO)
-	if (bbmiiphy)
-		bb_miiphy_free(container_of(priv->bus, struct bb_miiphy_bus, mii));
-	else
-#endif
-		mdio_free(priv->bus);
+	mdio_free(priv->bus);
 mdio_err:
 
 #ifdef CONFIG_CLK