net: dsa: bcm_sf2: Propagate error value from mdio_write

Both bcm_sf2_sw_indir_rw and mdiobus_write_nested could fail, so let's
return their error codes upstream.
Signed-off-by: NKangjie Lu <kjlu@umn.edu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/bcm_sf2.c

@@ -303,11 +303,10 @@ static int bcm_sf2_sw_mdio_write(struct mii_bus *bus, int addr, int regnum,
 	 * send them to our master MDIO bus controller
 	 */
 	if (addr == BRCM_PSEUDO_PHY_ADDR && priv->indir_phy_mask & BIT(addr))
-		bcm_sf2_sw_indir_rw(priv, 0, addr, regnum, val);
+		return bcm_sf2_sw_indir_rw(priv, 0, addr, regnum, val);
 	else
-		mdiobus_write_nested(priv->master_mii_bus, addr, regnum, val);
-
-	return 0;
+		return mdiobus_write_nested(priv->master_mii_bus, addr,
+				regnum, val);
 }
 
 static irqreturn_t bcm_sf2_switch_0_isr(int irq, void *dev_id)