arch: powerpc: mpc85xx: free MDIO bus if mdio_register fails

If mdio_register fails, it is nice to not leave behind dangling
allocated memory.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

arch/powerpc/cpu/mpc85xx/ether_fcc.c

@@ -449,8 +449,10 @@ int fec_initialize(struct bd_info *bis)
 		mdiodev->write = bb_miiphy_write;
 
 		retval = mdio_register(mdiodev);
-		if (retval < 0)
+		if (retval < 0) {
+			mdio_free(mdiodev);
 			return retval;
+		}
 #endif
 	}