staging/sbe-2t3e3: Use netdev_ printks in cpld.c

fixed below checkpatch warning.
- WARNING: Prefer netdev_err(netdev, ... then dev_err(dev, ... then pr_err(...  to printk(KERN_ERR ...
Signed-off-by: YAMANE Toshiaki <yamanetoshi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sbe-2t3e3/cpld.c

@@ -338,7 +338,7 @@ void cpld_set_fractional_mode(struct channel *sc, u32 mode,
 			   SBE_2T3E3_CPLD_VAL_FRACTIONAL_MODE_2);
 		break;
 	default:
-		printk(KERN_ERR "wrong mode in set_fractional_mode\n");
+		netdev_err(sc->dev, "wrong mode in set_fractional_mode\n");
 		return;
 	}