mlx4_en: Added missing iounmap upon releasing a device

mlx4_en: Added missing iounmap upon releasing a device

commit 7398af403f621418fa05c6936cac34aa06b5a758
Author: Alexander Guller <alexg@mellanox.com>
Date:   Sun Oct 9 05:27:11 2011 +0000

    mlx4_en: Added missing iounmap upon releasing a device

    Fixed a memory leak caused by missing iounmap when device
    is being released.

    Signed-off-by: Alexander Guller <alexg@mellanox.co.il>
    Signed-off-by: Sharon Cohen <sharonc@mellanox.co.il>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Joe Jin <joe.jin@oracle.com>