hidl_test: Fix failing tests.

Test: The following succeeds.
croot && cd hardware/interfaces
mma
croot && cd system/tools/hidl
mma
adb shell /data/nativetest64/hidl_test/hidl_test

Bug: 31819198

Change-Id: I40c2338d09d5e80b9bad2d918b7b8c3f2709f434