bta: Properly initialize bta::dm::disc::bta_dm_search_cb am: 100f3d68 am:...

bta: Properly initialize bta::dm::disc::bta_dm_search_cb am: 100f3d68 am: 3ad954a7 am: fff9f652

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Bluetooth/+/2825175



Change-Id: Ia1ce61a24ff78050da0cf9f988825f9263067c1d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>