Add boot parameter "instbootorder" to adjust boot order. By default
"starlingx" is the first boot target. Set "instbootorder" to "last"
can set "starlingx" as the last boot target.
Test Plan:
Pass: build-pkgs -c -p initramfs-ostree
Story: 2010643
Task: 48708
Signed-off-by: Zhang Xiao <xiao.zhang@windriver.com>
Change-Id: Ib0dea16194f570b3f9ad442666ca1db471653b0f
d4151146e4