[fdt] Add function to get the first range in /memory node of fdt am: 2422bdc31e am: 50dbcf7b27

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/2619458

Change-Id: I86f0ee312b49db649206e8810d29dcdfc74d78b9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>