[SCSI] gdth: gdth_interrupt() gdth_get_status() & gdth_wait() fixes

  - gdth_get_status() returns a single device interrupt IStatus
  - gdth_interrupt split to __gdth_interrupt() that receives
    flags if is called from gdth_wait().
  - Use dev_id passed from kernel and do not loop on all
    controllers.
  - gdth_wait(), get read of all global variables and call the new
    __gdth_interrupt with these variables on the stack

Signed-off-by Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>