net/mlx4_en: Cleanups suggested by clang static checker

clang flagged the following. All are actually cosmetic cleanups, not really bugs:

drivers/net/ethernet/mellanox/mlx4/en_main.c:233:3: warning: Value stored to 'err' is never read
                err = -ENOMEM;
                ^     ~~~~~~~
drivers/net/ethernet/mellanox/mlx4/en_main.c:293:3: warning: Value stored to 'err' is never read
                err = -ENOMEM;

drivers/net/ethernet/mellanox/mlx4/en_netdev.c:648:16: warning: Assigned value is garbage or undefined
        entry->reg_id = reg_id;
                      ^ ~~~~~~
drivers/net/ethernet/mellanox/mlx4/en_netdev.c:659:2: warning: Function call argument is an uninitialized value
        mlx4_en_uc_steer_release(priv, priv->dev->dev_addr, *qpn, reg_id);
(NOTE: reg_id is only used in the device-managed flow steering path, in which is it always initialized.
 This is not a bug. Cleanup here is therefore cosmetic only).

drivers/net/ethernet/mellanox/mlx4/en_rx.c:122:3: warning: Value stored to 'frag_info' is never read
                frag_info = &priv->frag_info[i];
                ^           ~~~~~~~~~~~~~~~~~~~
Signed-off-by: NJack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: NAmir Vadai <amirv@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_main.c

@@ -221,15 +221,12 @@ static void *mlx4_en_add(struct mlx4_dev *dev)
 {
 	struct mlx4_en_dev *mdev;
 	int i;
-	int err;
 
 	printk_once(KERN_INFO "%s", mlx4_en_version);
 
 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
-	if (!mdev) {
-		err = -ENOMEM;
+	if (!mdev)
 		goto err_free_res;
-	}
 
 	if (mlx4_pd_alloc(dev, &mdev->priv_pdn))
 		goto err_free_dev;
@@ -264,8 +261,7 @@ static void *mlx4_en_add(struct mlx4_dev *dev)
 	}
 
 	/* Build device profile according to supplied module parameters */
-	err = mlx4_en_get_profile(mdev);
-	if (err) {
+	if (mlx4_en_get_profile(mdev)) {
 		mlx4_err(mdev, "Bad module parameters, aborting\n");
 		goto err_mr;
 	}
@@ -286,10 +282,8 @@ static void *mlx4_en_add(struct mlx4_dev *dev)
 	 * Note: we cannot use the shared workqueue because of deadlocks caused
 	 *       by the rtnl lock */
 	mdev->workqueue = create_singlethread_workqueue("mlx4_en");
-	if (!mdev->workqueue) {
-		err = -ENOMEM;
+	if (!mdev->workqueue)
 		goto err_mr;
-	}
 
 	/* At this stage all non-port specific tasks are complete:
 	 * mark the card state as up */

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

@@ -575,7 +575,7 @@ static int mlx4_en_get_qp(struct mlx4_en_priv *priv)
 	struct mlx4_mac_entry *entry;
 	int index = 0;
 	int err = 0;
-	u64 reg_id;
+	u64 reg_id = 0;
 	int *qpn = &priv->base_qpn;
 	u64 mac = mlx4_mac_to_u64(priv->dev->dev_addr);
 

drivers/net/ethernet/mellanox/mlx4/en_rx.c

@@ -119,7 +119,6 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
 
 out:
 	while (i--) {
-		frag_info = &priv->frag_info[i];
 		if (page_alloc[i].page != ring_alloc[i].page) {
 			dma_unmap_page(priv->ddev, page_alloc[i].dma,
 				page_alloc[i].page_size, PCI_DMA_FROMDEVICE);