IB/mlx5: remove redundant assignment of mdev

The initial assignment to mdev is redundant as mdev is re-assigned
later and the first assigned value is never read. Remove this
redundant assignment.

Cleans up clang warning:
drivers/infiniband/hw/mlx5/main.c:359:24: warning: Value stored
to 'mdev' during its initialization is never read
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/main.c

@@ -356,7 +356,7 @@ static int mlx5_query_port_roce(struct ib_device *device, u8 port_num,
 				struct ib_port_attr *props)
 {
 	struct mlx5_ib_dev *dev = to_mdev(device);
-	struct mlx5_core_dev *mdev = dev->mdev;
+	struct mlx5_core_dev *mdev;
 	struct net_device *ndev, *upper;
 	enum ib_mtu ndev_ib_mtu;
 	bool put_mdev = true;