[SCSI] aic7xxx: fix ahc_done check SCB_ACTIVE for tagged transactions

The driver only needs to check the SCB_ACTIVE flag if the SCB is not
in the untagged queue.

If the driver is in error recovery, you may end panic'ing on a TUR
that is in the untagged queue.

Attempting to queue an ABORT message
CDB: 0x0 0x0 0x0 0x0 0x0 0x0
SCB 3 done'd twice

This patch is included in Adaptec's 6.3.11 driver on their website.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>