Bluetooth-OPP: Cleanup pending share while BT turn OFF

This will ensure that pending OPP shares will be removed from database
while BT is turning OFF. Otherwise, BT turned back ON if there are some
pending share in database it will start sending automatically.

CRs-Fixed: 611970
Change-Id: Ibc2664840f11bfeaefb5984e8ac18a171d515129