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 am: 1b5e1b4c

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



Change-Id: I045ec77de68604827cdd1a2de84066281ecc7f60
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>