[automerge] libfdt: fdt_path_offset_namelen: Reject empty paths 2p: a6ac6d916d 2p: c69e9730e6

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/dtc/+/20024810

Bug: 246465319
Change-Id: I9096ca5ab6c194d2512e3c902a9658c33a40ff0c