[SCSI] qla1280: Fix queue depth problem

The qla1280 driver was ANDing the output value of mailbox register
0 with (1 << target-number) to determine whether to enable queueing
on the target in question.

But mailbox register 0 has the status code for the mailbox command
(in this case, Set Target Parameters). Potential values are:
/*
* ISP mailbox command complete status codes
*/

So clearly that is in error. I can't think what the author of that
line was looking for in a mailbox register, so I just eliminated the
AND. flag is used later in the function, and I think that the later
usage was also wrong, though it was used to set values that aren't
used. Oh well, an overhaul of this driver is not what I want to do
now -- just a bugfix.

After the fix, I found that my disks were getting a queue depth of
255, which is far too many. Most SCSI disks are limited to 32 or
64. In any case, there's no point, queueing up a bunch of commands
to the adapter that will just result in queue full or starve other
targets from being issued commands due to running out of internal
memory. So I dropped default queue depth to 32 (from which 1 is
subtracted elsewhere, giving net of 31).

I tested with a Seagate ST336753LC, and results look good, so
I'm satisfied with this patch.

Signed-off-by: Jeremy Higdon <[e-mail]>
Acked-by: Jes Sorensen <[e-mail]>
Cc: Stable Tree <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/qla1280.c

···
 		nv->bus[bus].config_2.req_ack_active_negation = 1;
 		nv->bus[bus].config_2.data_line_active_negation = 1;
 		nv->bus[bus].selection_timeout = 250;
-		nv->bus[bus].max_queue_depth = 256;
+		nv->bus[bus].max_queue_depth = 32;
 
 		if (IS_ISP1040(ha)) {
 			nv->bus[bus].bus_reset_delay = 3;
···
 	status = qla1280_mailbox_command(ha, 0x0f, mb);
 
 	/* Save Tag queuing enable flag. */
-	flag = (BIT_0 << target) & mb[0];
+	flag = (BIT_0 << target);
 	if (nv->bus[bus].target[target].parameter.tag_queuing)
 		ha->bus_settings[bus].qtag_enables |= flag;