[SCSI] sr: update to follow tray status correctly

Based on an original patch from: David Martin <tasio@tasio.net>

When trying to get the drive status via ioctl CDROM_DRIVE_STATUS, with
no disk it gives CDS_TRAY_OPEN even if the tray is closed.

ioctl works as expected with ide-cd driver.

Gentoo bug report: http://bugs.gentoo.org/show_bug.cgi?id=196879

Cc: Maarten Bressers <mbres@gentoo.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h
index 0d04e28..81fbc0b 100644
--- a/drivers/scsi/sr.h
+++ b/drivers/scsi/sr.h
@@ -20,6 +20,9 @@
 #include <linux/genhd.h>
 #include <linux/kref.h>
 
+#define MAX_RETRIES	3
+#define SR_TIMEOUT	(30 * HZ)
+
 struct scsi_device;
 
 /* The CDROM is fairly slow, so we need a little extra time */