Fix NPE on tearDown when TV ASSUMPTION_FAILED When a VirtualDeviceTestCase runs into an ASSUMPTION_FAILED on TV devices, it erroneously attempts to clean up a null pointer during cleanup. Fixes: 288002171 Test: Local atest run. (cherry picked from https://googleplex-android-review.googlesource.com/q/commit:e8bc859ff94b30bcabe1b57d5d9d43723c9391fa) (cherry picked from https://googleplex-android-review.googlesource.com/q/commit:638809def1aada7b758bf2ea5d00b8af5496e77c) Merged-In: I19681122af6b9ef67a66bfbcda3f0eed48ac2c43 Change-Id: I19681122af6b9ef67a66bfbcda3f0eed48ac2c43