Drop duplicate service state check.

We already are checking this in sendDeviceStateChanged(), and
onServiceStateChanged() and onSignalStrengthsChanged() have no defined
order, so the signal strength information is lost in case
onSignalStrengthsChanged() is called first.

Change-Id: Id419135780ed7ec58016e32fa37ea06c74ac07d4
(cherry picked from commit d4d21f7a1797e316d392e179d923d4c12dca36fa)