scsi: sr: Return correct event when media event code is 3

Media event code 3 is defined in the MMC-6 spec as follows:

  "MediaRemoval: The media has been removed from the specified slot, and
   the Drive is unable to access the media without user intervention. This
   applies to media changers only."

This indicated that treating the condition as an EJECT_REQUEST was
appropriate. However, doing so had the unfortunate side-effect of causing
the drive tray to be physically ejected on resume. Instead treat the event
as a MEDIA_CHANGE request.

Fixes: 7dd753c ("scsi: sr: Return appropriate error code when disk is ejected")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213759
Link: https://lore.kernel.org/r/20210726114913.6760-1-limanyi@uniontech.com
Signed-off-by: Li Manyi <limanyi@uniontech.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sr.c

@@ -221,7 +221,7 @@ static unsigned int sr_get_events(struct scsi_device *sdev)
 	else if (med->media_event_code == 2)
 		return DISK_EVENT_MEDIA_CHANGE;
 	else if (med->media_event_code == 3)
-		return DISK_EVENT_EJECT_REQUEST;
+		return DISK_EVENT_MEDIA_CHANGE;
 	return 0;
 }