init-install.sh: Fix make partition and make file system issues
[YOCTO #1151]
Change the offset from the beginning of the disk to aligne the blocks.
In this script, we use mkfs.ext3 to create file system after partition, but we use mkpartfs to create file system repeatly,
and get some warnings about choose another specific tools to create file system for reliability.
So use mkpart instead of mkpartfs and only use mkfs.ext3 to create file system.
