cciss: decode unit attention in SCSI error handling code

Make SCSI reset error handler decode unit attention ASC
and after a target reset wait for a unit attention that indicates
a reset occurred rather than just for any old unit attention.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>