boot: Allow boot order=g-m option to choose boot SCSI ID

Add support to boot from a specific SCSI ID by mapping drives
g-m to SCSI IDs 0-7, e.g.
 -boot order=g  for SCSI ID 0, and
 -boot order=l  for SCSI ID 5

Signed-off-by: Helge Deller <deller@gmx.de>
1 file changed