Merge "HWC2: Clarify null client target handle" into nyc-dev
am: 0154a6b08d

* commit '0154a6b08d8bd1f87bc519713369e30bb5bd4146':
  HWC2: Clarify null client target handle

Change-Id: I27e8198dbb136f5bdd1927634a3e553df00494ee