scsi/i2o: restore ioctl changes

This restores the changes from "scsi/i2o_block: cleanup ioctl
handling", which accidentally got reverted.

Origignal changelog:
      This fixes the ioctl function of the i2o_block driver, which
      has multiple problems:

      * The BLKI2OSRSTRAT and BLKI2OSWSTRAT commands always return
        -ENOTTY on success, where they should return 0.
      * Support for 32 bit compat is missing
      * The driver should use the .ioctl function and because
        .locked_ioctl is going away.

      The use of the big kernel lock remains for now, but gets
      made explictit in the ioctl function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>