healthd: charger: fix check for charger connected to enter suspend

Logic for this check was inadvertently reversed when porting this from
the charger daemon to healthd.  Request suspend if a charegr is connected,
else stay out of suspend waiting for a charger connect or power off if
none.

Bug: 17112463
Change-Id: Iffdb6dbcd0d0a2a614ff8f50bf5f2e22e1ad552f