scsi: scsi_error: Handle power-on reset unit attention

As per SAM there is a status precedence, with any sense code 29/XX
taking second place just after an ACA ACTIVE status.  Additionally, each
target might prefer to not queue any unit attention conditions, but just
report one.  Due to the above, this will be that one with the highest
precedence.  This results in the sense code 29/XX effectively
overwriting any other unit attention.  Hence we should report the
power-on reset to userland so that it can take appropriate action.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>