net: dsa: bcm_sf2: stop assigning an OF node to the ds->user_mii_bus

The bcm_sf2 driver does something strange. Instead of calling
of_mdiobus_register() with an OF node argument, it manually assigns the
bus->dev->of_node and then calls the non-OF mdiobus_register(). This
circumvents some code from __of_mdiobus_register() from running, which
sets the auto-scan mask, parses some device tree properties, etc.

I'm going to go out on a limb and say that the OF node isn't, in fact,
needed at all, and can be removed. The MDIO diversion as initially
implemented in commit 461cd1b ("net: dsa: bcm_sf2: Register our
slave MDIO bus") looked quite different than it is now, after commit
771089c ("net: dsa: bcm_sf2: Ensure that MDIO diversion is used").
Initially, it made sense, as bcm_sf2 was registering another set of
driver ops for the "brcm,unimac-mdio" OF node. But now, it deletes all
phandles, which makes "phy-handle"s unable to find PHYs, which means
that it always goes through the OF-unaware dsa_user_phy_connect().

Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Alvin Šipraga <[email protected]>
Reviewed-by: Florian Fainelli <[email protected]>
Tested-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

drivers/net/dsa/bcm_sf2.c

@@ -635,7 +635,6 @@ static int bcm_sf2_mdio_register(struct dsa_switch *ds)
 	priv->user_mii_bus->write = bcm_sf2_sw_mdio_write;
 	snprintf(priv->user_mii_bus->id, MII_BUS_ID_SIZE, "sf2-%d",
 		 index++);
-	priv->user_mii_bus->dev.of_node = dn;
 
 	/* Include the pseudo-PHY address to divert reads towards our
 	 * workaround. This is only required for 7445D0, since 7445E0