mpc83xx: Fix the UEC driver bug of QE

The patch prevents the GCC tool chain from striping useful code for
optimization. It will make UEC ethernet driver workable, Otherwise the
UEC will fail in tx when you are using gcc4.x. but the driver can work
when using gcc3.4.3.

CHANGELOG

*Prevent the GCC from striping code for optimization, Otherwise the UEC
will tx failed when you are using gcc4.x.

Signed-off-by: Dave Liu <daveliu@freescale.com>
diff --git a/drivers/qe/uec.c b/drivers/qe/uec.c
index f640c81..c44a5be 100644
--- a/drivers/qe/uec.c
+++ b/drivers/qe/uec.c
@@ -1122,7 +1122,7 @@
 	uec_private_t		*uec;
 	ucc_fast_private_t	*uccf;
 	volatile qe_bd_t	*bd;
-	volatile u16		status;
+	u16			status;
 	int			i;
 	int			result = 0;
 
@@ -1131,7 +1131,7 @@
 	bd = uec->txBd;
 
 	/* Find an empty TxBD */
-	for (i = 0; BD_STATUS(bd) & TxBD_READY; i++) {
+	for (i = 0; bd->status & TxBD_READY; i++) {
 		if (i > 0x100000) {
 			printf("%s: tx buffer not ready\n", dev->name);
 			return result;
@@ -1150,13 +1150,11 @@
 	ucc_fast_transmit_on_demand(uccf);
 
 	/* Wait for buffer to be transmitted */
-	status = BD_STATUS(bd);
-	for (i = 0; status & TxBD_READY; i++) {
+	for (i = 0; bd->status & TxBD_READY; i++) {
 		if (i > 0x100000) {
 			printf("%s: tx error\n", dev->name);
 			return result;
 		}
-		status = BD_STATUS(bd);
 	}
 
 	/* Ok, the buffer be transimitted */
@@ -1171,12 +1169,12 @@
 {
 	uec_private_t		*uec = dev->priv;
 	volatile qe_bd_t	*bd;
-	volatile u16		status;
+	u16			status;
 	u16			len;
 	u8			*data;
 
 	bd = uec->rxBd;
-	status = BD_STATUS(bd);
+	status = bd->status;
 
 	while (!(status & RxBD_EMPTY)) {
 		if (!(status & RxBD_ERROR)) {
@@ -1190,7 +1188,7 @@
 		BD_LENGTH_SET(bd, 0);
 		BD_STATUS_SET(bd, status | RxBD_EMPTY);
 		BD_ADVANCE(bd, status, uec->p_rx_bd_ring);
-		status = BD_STATUS(bd);
+		status = bd->status;
 	}
 	uec->rxBd = bd;