Refactor: libstonithd: Replace stonith__device_parameter_flags()

...with stonith__param_is_supported().

The parameter flags are the only stonith device flags used outside of
the fencer. This will allow us to move the flag enum into the fencer.

Two lines in the fencer become longer than 80 characters because the
flag names are so long, but this is temporary.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>