scsi: sr: Return appropriate error code when disk is ejected

Handle a reported media event code of 3. This indicates that the media has
been removed from the drive and user intervention is required to proceed.
Return DISK_EVENT_EJECT_REQUEST in that case.

Link: https://lore.kernel.org/r/20210611094402.23884-1-limanyi@uniontech.com


Signed-off-by: ManYi Li <limanyi@uniontech.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>