net/mlx5e: Priv state flag not rolled-back upon netdev open error

The private mlx5 state flag that indicates that the netdev is
opened is set at the beginning of the netdev open flow.
In case an error occured later in the mlx5 netdev open flow, this
flag was not cleared, remaining set although the actual set is
closed.

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>