net: dsa: bcm_sf2: Utilize nested MDIO read/write

We are implementing a MDIO bus which is behind another one, so use the
nested version of the accessors to get lockdep annotations correct.

Fixes: 461cd1b03e ("net: dsa: bcm_sf2: Register our slave MDIO bus")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/bcm_sf2.c

@@ -393,7 +393,7 @@ static int bcm_sf2_sw_mdio_read(struct mii_bus *bus, int addr, int regnum)
 	if (addr == BRCM_PSEUDO_PHY_ADDR && priv->indir_phy_mask & BIT(addr))
 		return bcm_sf2_sw_indir_rw(priv, 1, addr, regnum, 0);
 	else
-		return mdiobus_read(priv->master_mii_bus, addr, regnum);
+		return mdiobus_read_nested(priv->master_mii_bus, addr, regnum);
 }
 
 static int bcm_sf2_sw_mdio_write(struct mii_bus *bus, int addr, int regnum,
@@ -407,7 +407,7 @@ static int bcm_sf2_sw_mdio_write(struct mii_bus *bus, int addr, int regnum,
 	if (addr == BRCM_PSEUDO_PHY_ADDR && priv->indir_phy_mask & BIT(addr))
 		bcm_sf2_sw_indir_rw(priv, 0, addr, regnum, val);
 	else
-		mdiobus_write(priv->master_mii_bus, addr, regnum, val);
+		mdiobus_write_nested(priv->master_mii_bus, addr, regnum, val);
 
 	return 0;
 }