drivers: net: xgene: Simplify xgene_enet_setup_mss() to kill warning

With gcc-4.1.2 and -Os:

    drivers/net/ethernet/apm/xgene/xgene_enet_main.c: In function ‘xgene_enet_start_xmit’:
    drivers/net/ethernet/apm/xgene/xgene_enet_main.c:297: warning: ‘mss_index’ may be used uninitialized in this function

Using a separate variable to track success may confuse the compiler.
Preinitialize mss_index with -EBUSY and check for negative error values
instead to kill the warning.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/apm/xgene/xgene_enet_main.c

@@ -293,36 +293,29 @@ static int xgene_enet_tx_completion(struct xgene_enet_desc_ring *cp_ring,
 static int xgene_enet_setup_mss(struct net_device *ndev, u32 mss)
 {
 	struct xgene_enet_pdata *pdata = netdev_priv(ndev);
-	bool mss_index_found = false;
-	int mss_index;
+	int mss_index = -EBUSY;
 	int i;
 
 	spin_lock(&pdata->mss_lock);
 
 	/* Reuse the slot if MSS matches */
-	for (i = 0; !mss_index_found && i < NUM_MSS_REG; i++) {
+	for (i = 0; mss_index < 0 && i < NUM_MSS_REG; i++) {
 		if (pdata->mss[i] == mss) {
 			pdata->mss_refcnt[i]++;
 			mss_index = i;
-			mss_index_found = true;
 		}
 	}
 
 	/* Overwrite the slot with ref_count = 0 */
-	for (i = 0; !mss_index_found && i < NUM_MSS_REG; i++) {
+	for (i = 0; mss_index < 0 && i < NUM_MSS_REG; i++) {
 		if (!pdata->mss_refcnt[i]) {
 			pdata->mss_refcnt[i]++;
 			pdata->mac_ops->set_mss(pdata, mss, i);
 			pdata->mss[i] = mss;
 			mss_index = i;
-			mss_index_found = true;
 		}
 	}
 
-	/* No slots with ref_count = 0 available, return busy */
-	if (!mss_index_found)
-		mss_index = -EBUSY;
-
 	spin_unlock(&pdata->mss_lock);
 
 	return mss_index;