Merge "Remove unused Android.mk under contexthub/firmware/os" into main am: 09796949a1

Original change: https://android-review.googlesource.com/c/device/google/contexthub/+/3081466

Change-Id: Ibcc09eed68411a2cc1dade356668d2462aeb8963
Signed-off-by: Automerger Merge Worker <[email protected]>