Pass 1:0x96 instead of 4:0x96 to bootilnx.mksh to use first partition as boot system.

Linux fdisk expects partitions in on-disc order. When using
4:0x96 there's only one partition, being sdX4. If a user creates
a new partition then it's called sdX1 but gets shown after sdX4.
Let's try to stop the confusion and use first partition for the
iso9660 system.

Thanks: Thorsten Glaser <tg@mirbsd.org>