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
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:d3753ec91db5416f939e633e5020f50ced84c0e9)
Merged-In: I83081cbef66da1d74d87e191f266cb16fb559b85
Change-Id: I83081cbef66da1d74d87e191f266cb16fb559b85