Remove unused Android.mk under device/google/redfin am: a9544cd2ed am: 2156e0d5ed

Original change: https://android-review.googlesource.com/c/device/google/redfin/+/2836011

Change-Id: I3e2e4b292d167feb0bebfc0d99d15beeb5c9f328
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>