ncr5380: Standardize work queueing algorithm

The complex main_running/queue_main mechanism is peculiar to
atari_NCR5380.c. It isn't SMP safe and offers little value given that
the work queue already offers concurrency management. Remove this
complexity to bring atari_NCR5380.c closer to NCR5380.c.

It is not a good idea to call the information transfer state machine from
queuecommand because, according to Documentation/scsi/scsi_mid_low_api.txt
that could happen in soft irq context. Fix this.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/NCR5380.h

@@ -262,7 +262,6 @@ struct NCR5380_hostdata {
 	                                   * transfer to handle chip overruns */
 	int retain_dma_intr;
 	struct work_struct main_task;
-	volatile int main_running;
 #ifdef SUPPORT_TAGS
 	struct tag_alloc TagAlloc[8][8];	/* 8 targets and 8 LUNs */
 #endif