camera: Fix prefix length path for External Camera HAL am: b8863f6a03 am: e1390f059f am: f617111ca5

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2386907

Change-Id: I0d1a4f3fcb4747dfac1d3f98e967d0b2bd8e6646
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>