[SCSI] gdth: clean up host private data

  - Based on same patch from Christoph Hellwig <hch@lst.de>

  - Get rid of all the indirection in the Scsi_Host private data and always
    put the gdth_ha_str directly into it.

  - Change all internal functions prototype to recieve an "gdth_ha_str *ha"
    pointer directlly and kill all that redundent access to the "gdth_ctr_tab[]"
    controller-table.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>