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: 7d2ef30e am: 20c92279

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



Change-Id: Ie803407cdea22cbc89d3f991635dcf20b5420d48
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>