Recover cleanly from power HAL service crashes

Currently if the binderized power HAL service crashes, services that
call the HAL will crash as well. To fix this:
- Before calling power HAL functions, check that the handle to the
  power HAL service is still valid, and reload using getService() if
  necessary.
- When a call to a power HAL function fails, log the failure and mark
  the handle as invalid.

Bug: 35728909
Test: adb shell kill -9 $(adb shell pidof android.hardware.power@1.0-service)
Change-Id: Id2dd1a6507b9f5044d928483cdb6b736c701f8ba
Signed-off-by: Connor O'Brien <connoro@google.com>