Revert "scsi: ncr5380: Increase register polling limit"

This reverts commit 4822827a.

The purpose of that commit was to suppress a timeout warning message which
appeared to be caused by target latency. But suppressing the warning is
undesirable as the warning may indicate a messed up transfer count.

Another problem with that commit is that 15 ms is too long to keep
interrupts disabled as interrupt latency can cause system clock drift and
other problems.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 4822827a ("scsi: ncr5380: Increase register polling limit")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/NCR5380.h

@@ -235,7 +235,7 @@ struct NCR5380_cmd {
 #define NCR5380_PIO_CHUNK_SIZE		256
 
 /* Time limit (ms) to poll registers when IRQs are disabled, e.g. during PDMA */
-#define NCR5380_REG_POLL_TIME		15
+#define NCR5380_REG_POLL_TIME		10
 
 static inline struct scsi_cmnd *NCR5380_to_scmd(struct NCR5380_cmd *ncmd_ptr)
 {