Fix null pointer deref in libsensor SensorServer

When trying to create a senor direct connection, check that native
handle resource is not null, and if so return BAD_VALUE error.

Bug: 135051254
Test: Load onto device and try "service call sensorservice 5"
commands that have no arguments and random arguments. Both throw  new error
and do not crash system as hoped.

Change-Id: Ie2eaf1a17843da89927293e408768bfbaaf86ec8