Remove constant var tBTM_CB::tBTM_BLE_CB::tBTM_BLE_INQ_CB::scan_duplicate_filter

Always set to same value

Towards readable code

Bug: 163134718
Tag: #refactor
Test: acts -tc BleCocTest
Test: ble paired 2 phones

Change-Id: I808a6fd2466d7f72f0ab41d2862e3bf64910f718