clarify set failure due to power down

- some properties can have separate propety control power state
  and setting such property when it is powered off should
  lead into returning error from hal. Define -ESHUTDOWN as
  error code to use in such case.

bug: 28385609
Change-Id: I41c1519ad00b43a83f3aa4e5f0627d75d87a960b
1 file changed