Add demux to mFrontendTests am: 86aa7010fd

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2886926

Change-Id: I422f6448d26a5e5f2e7915309636503ac92e2c7d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>