VTSHalPowerTarget: Add condition check for FMQAidl teardown

While FMQAidl Setup() was skipped, some uninitialized objects would be
used in FMQAidl Teardown() which caused the test failed.
Add some condition check to prevent from using uninitialized objects.

Test: atest VTSHalPowerTarget
Bug: 328330332
Change-Id: I83081cbef66da1d74d87e191f266cb16fb559b85
(cherry picked from commit d3753ec9)