[SCSI] qla4xxx: Remove reduandant code after open-iscsi integration.

1. Remove device database entry (ddb) state.
2. Remove device database (DDB) list building.
                With open-iscsi integration the logins to the target devices are
        handled by the user space. So the information of target is now
        maintained in the iscsi_session object. This is handled at
        libiscsi level so there is no need to maintain a list of DDBs in
        the qla4xxx LLD.
3. qla4xxx: Remove add_device_dynamically.
                Since autologin in FW is disabled with open-iscsi integration,
        driver will never get an AEN for which driver has not requested
        a DDB index. So remove the add_device_dynamically function.
4. Remove qla4xxx_tgt_dscvr
        Since firmware autologin is disabled this function will not work.
        Now user has the ability to do the target discovery and login to
        each target individually. Firwmare will not do the login on its own.
5. Remove relogin related code
        All relogin is handled by userspace now. qla4xxx just need to
        notify userspace of a connection failure, this triggers the
        relogin.
6. Remove add_session and alloc_session
        Now qla4xxx uses iscsi_session_setup that would do the necessary
        allocations for session and ddb_entry.

Signed-off-by: Manish Rangankar <manish.rangankar@qlogic.com>
Signed-off-by: Lalit Chandivade <lalit.chandivade@qlogic.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>