Use dynamic partition size am: b416ba5dc4 am: d2d44ac273

Original change: https://android-review.googlesource.com/c/platform/system/tools/mkbootimg/+/3482251

Change-Id: I72ba3219acd3adf117fcd96e7a8853ee97b17730
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>