Merge "power/stats: Adding subsystem field to Channel" into sc-dev am: 6527c0e763

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/interfaces/+/13412798

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I12f06bb9fc2484b3f57f7d71ee19f18d3cb2d719