Merge "doc: DEVICE_*_MATRIX_FILE specifies absolute paths" am: cc6279316f am: 4e7d50fe01 am: dfb4a153dd am: 7bafc1ab96

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1455056

Change-Id: I8a22058e25999bf6617d50314a1f61f817b656e1