net/mlx5: Bridge, fix uninitialized variable usage

In some conditions variable 'err' is not assigned with value in
mlx5_esw_bridge_port_obj_attr_set() and mlx5_esw_bridge_port_changeupper()
functions after recent changes to support LAG. Initialize the variable with
zero value in both cases.
Reported-by: Colin King <colin.king@canonical.com>
Reported-by: Tim Gardner <tim.gardner@canonical.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
CC: linux-kernel@vger.kernel.org
Fixes: ff9b7521 ("net/mlx5: Bridge, support LAG")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/rep/bridge.c

@@ -137,7 +137,7 @@ static int mlx5_esw_bridge_port_changeupper(struct notifier_block *nb, void *ptr
 	u16 vport_num, esw_owner_vhca_id;
 	struct netlink_ext_ack *extack;
 	int ifindex = upper->ifindex;
-	int err;
+	int err = 0;
 
 	if (!netif_is_bridge_master(upper))
 		return 0;
@@ -244,7 +244,7 @@ mlx5_esw_bridge_port_obj_attr_set(struct net_device *dev,
 	struct netlink_ext_ack *extack = switchdev_notifier_info_to_extack(&port_attr_info->info);
 	const struct switchdev_attr *attr = port_attr_info->attr;
 	u16 vport_num, esw_owner_vhca_id;
-	int err;
+	int err = 0;
 
 	if (!mlx5_esw_bridge_lower_rep_vport_num_vhca_id_get(dev, br_offloads->esw, &vport_num,
 							     &esw_owner_vhca_id))