qla2xxx: Move mailbox failure messages to a default debug level.

Move the mailbox failure messages to a default debugging level so that
benign failures won't flood the system logs but will still show up if
default debug messaging is enabled (ql2xextended_error_logging=1).
Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/qla2xxx/qla_mbx.c

@@ -373,7 +373,7 @@ qla2x00_mailbox_command(scsi_qla_host_t *vha, mbx_cmd_t *mcp)
 
 mbx_done:
 	if (rval) {
-		ql_log(ql_log_warn, base_vha, 0x1020,
+		ql_dbg(ql_dbg_disc, base_vha, 0x1020,
 		    "**** Failed mbx[0]=%x, mb[1]=%x, mb[2]=%x, mb[3]=%x, cmd=%x ****.\n",
 		    mcp->mb[0], mcp->mb[1], mcp->mb[2], mcp->mb[3], command);
 	} else {