libfdt: fdt_path_offset_namelen: Reject empty paths am: d10c84c4bc

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/dtc/+/20024811

Change-Id: Ia05c202fb0033659b334390610479f0ed0e591cb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>