Remove unused Android.mk under device/google/contexthub am: 2c51922b31 am: 9bfc0e39ab

Original change: https://android-review.googlesource.com/c/device/google/contexthub/+/3093623

Change-Id: Ia5b10d25cf6ad424ae2102aeb44e6d14983a2a7c
Signed-off-by: Automerger Merge Worker <[email protected]>