[SCSI] aic94xx: fix sequencer hang on error recovery

The clear nexus I_T and clear nexus I_T_L functions in the aic94xx
specify the SUSPEND_TX flag which causes the sequencer to be suspended
until it receives a RESUME_TX.  Unfortunately, nothing ever sends the
resume, so the sequencer on the link is stopped forever, leading to
eventual timeouts and I/O errors.

Since clear nexus commands are only executed as part of error recovery,
it's perfectly fine to keep the sequencer running on the link ... as
soon as the recovery function is completed, we'll send it the commands
to retry.

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