When deregister bta_sys_deregister set nullptr am: 5922eec9 am: f3e3385a...

When deregister bta_sys_deregister set nullptr am: 5922eec9 am: f3e3385a am: f0c5d279 am: 787a9545

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Bluetooth/+/2056574



Change-Id: I52ec9179eafdd7a1bd24594e34167f10f450ec10
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>