scsi-disk: allow MODE SELECT block descriptor to set the block size

scsi-disk: allow MODE SELECT block descriptor to set the block size

The MODE SELECT command can contain an optional block descriptor that can be used
to set the device block size. If the block descriptor is present then update the
block size on the SCSI device accordingly.

This allows CDROMs to be used with A/UX which requires a CDROM drive which is
capable of switching from a 2048 byte sector size to a 512 byte sector size.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220622105314.802852-13-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>