Flatten power manager wake lock constants.

We only support a few basic kinds of wake locks.  Rather than
pretend that we could support other weird combinations of features,
just get rid of the feature bits.

Deprecated other wake lock types.  We really want to encourage
developers to use FLAG_KEEP_SCREEN_ON instead of managing
their own wake locks, even though its behavior is not
exactly equivalent.

Change-Id: Idfeb0bc6efff0ef2736e47f72a06e69e5a16996e