mpc83xx: Fix alternating tx error / tx buffer not ready bug in QE UEC

The problem is not gcc4 but the code itself. The BD_STATUS() macro can't
be used for busy-waiting since it strips the 'volatile' property from
the bd variable. gcc3 was working by pure luck.

This is a follow on patch to "Fix the UEC driver bug of QE"

drivers/qe/uec.c

@@ -1148,7 +1148,7 @@ static int uec_send(struct eth_device* dev, volatile void *buf, int len)
 	/* Init TxBD */
 	BD_DATA_SET(bd, buf);
 	BD_LENGTH_SET(bd, len);
-	status = BD_STATUS(bd);
+	status = bd->status;
 	status &= BD_WRAP;
 	status |= (TxBD_READY | TxBD_LAST);
 	BD_STATUS_SET(bd, status);