[SCSI] sg: Remove aha1542 hack

Remove a hack in the sg driver that alters the total buffer
length for SG_IO commands to ensure buffers are not odd byte
lengths. This breaks on the ipr driver since it requires the
request_bufflen to equal the length specified in the cdb.
The block layer SG_IO code does not appear to have this hack.

Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: Brian King <brking@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>