Ensure OS-version/patch-level is passed to init_boot for lunches without kernel.

Split lunches (especially the system side lunch) can have init_boot
enabled without kernel, handle that case and continue to pass the
OS-version/patch-level values into the init_boot.img by setting them at
the right point.
(cherry picked from https://partner-android-review.googlesource.com/q/commit:ef3c245a444fb30a01dae61ef4d970dc733ac8f2)

Merged-In: Ia9cfcb49dfd2471104fc121b087a0eb3d44a0c41
Change-Id: Ia9cfcb49dfd2471104fc121b087a0eb3d44a0c41