dynamic_sensor: Add sensor manager init to sub-HAL 2.1. am: c7038f8a78 am: 409c42afad

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/libhardware/+/15874906

Change-Id: I790c826f327c71520a7ad20850686c41f7aaa0c5